1
|
Holendová B, Benáková Š, Křivonosková M, Plecitá-Hlavatá L. Redox Status as a Key Driver of Healthy Pancreatic Beta-Cells. Physiol Res 2024; 73:S139-S152. [PMID: 38647167 DOI: 10.33549/physiolres.935259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024] Open
Abstract
Redox status plays a multifaceted role in the intricate physiology and pathology of pancreatic beta-cells, the pivotal regulators of glucose homeostasis through insulin secretion. They are highly responsive to changes in metabolic cues where reactive oxygen species are part of it, all arising from nutritional intake. These molecules not only serve as crucial signaling intermediates for insulin secretion but also participate in the nuanced heterogeneity observed within the beta-cell population. A central aspect of beta-cell redox biology revolves around the localized production of hydrogen peroxide and the activity of NADPH oxidases which are tightly regulated and serve diverse physiological functions. Pancreatic beta-cells possess a remarkable array of antioxidant defense mechanisms although considered relatively modest compared to other cell types, are efficient in preserving redox balance within the cellular milieu. This intrinsic antioxidant machinery operates in concert with redox-sensitive signaling pathways, forming an elaborate redox relay system essential for beta-cell function and adaptation to changing metabolic demands. Perturbations in redox homeostasis can lead to oxidative stress exacerbating insulin secretion defect being a hallmark of type 2 diabetes. Understanding the interplay between redox signaling, oxidative stress, and beta-cell dysfunction is paramount for developing effective therapeutic strategies aimed at preserving beta-cell health and function in individuals with type 2 diabetes. Thus, unraveling the intricate complexities of beta-cell redox biology presents exciting avenues for advancing our understanding and treatment of metabolic disorders.
Collapse
Affiliation(s)
- B Holendová
- Laboratory of Pancreatic Islet Research, Czech Academy of Sciences, Prague 4, Czech Republic.
| | | | | | | |
Collapse
|
2
|
Puginier E, Leal-Fischer K, Gaitan J, Lallouet M, Scotti PA, Raoux M, Lang J. Extracellular electrophysiology on clonal human β-cell spheroids. Front Endocrinol (Lausanne) 2024; 15:1402880. [PMID: 38883608 PMCID: PMC11176477 DOI: 10.3389/fendo.2024.1402880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 05/06/2024] [Indexed: 06/18/2024] Open
Abstract
Background Pancreatic islets are important in nutrient homeostasis and improved cellular models of clonal origin may very useful especially in view of relatively scarce primary material. Close 3D contact and coupling between β-cells are a hallmark of physiological function improving signal/noise ratios. Extracellular electrophysiology using micro-electrode arrays (MEA) is technically far more accessible than single cell patch clamp, enables dynamic monitoring of electrical activity in 3D organoids and recorded multicellular slow potentials (SP) provide unbiased insight in cell-cell coupling. Objective We have therefore asked whether 3D spheroids enhance clonal β-cell function such as electrical activity and hormone secretion using human EndoC-βH1, EndoC-βH5 and rodent INS-1 832/13 cells. Methods Spheroids were formed either by hanging drop or proprietary devices. Extracellular electrophysiology was conducted using multi-electrode arrays with appropriate signal extraction and hormone secretion measured by ELISA. Results EndoC-βH1 spheroids exhibited increased signals in terms of SP frequency and especially amplitude as compared to monolayers and even single cell action potentials (AP) were quantifiable. Enhanced electrical signature in spheroids was accompanied by an increase in the glucose stimulated insulin secretion index. EndoC-βH5 monolayers and spheroids gave electrophysiological profiles similar to EndoC-βH1, except for a higher electrical activity at 3 mM glucose, and exhibited moreover a biphasic profile. Again, physiological concentrations of GLP-1 increased AP frequency. Spheroids also exhibited a higher secretion index. INS-1 cells did not form stable spheroids, but overexpression of connexin 36, required for cell-cell coupling, increased glucose responsiveness, dampened basal activity and consequently augmented the stimulation index. Conclusion In conclusion, spheroid formation enhances physiological function of the human clonal β-cell lines and these models may provide surrogates for primary islets in extracellular electrophysiology.
Collapse
Affiliation(s)
- Emilie Puginier
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
| | - Karen Leal-Fischer
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
| | - Julien Gaitan
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
| | - Marie Lallouet
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
| | - Pier-Arnaldo Scotti
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
| | - Matthieu Raoux
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
| | - Jochen Lang
- Univiversity of Bordeaux, CNRS, Bordeaux INP, Laboratoire de Chimie et Biologie des Membranes CBMN, UMR 5248, Pessac, Bordeaux, France
| |
Collapse
|
3
|
Sue N, Thai LM, Saito A, Boyer CK, Fordham AM, Yan C, Davenport A, Tao J, Bensellam M, Cantley J, Shi YC, Stephens SB, Imaizumi K, Biden TJ. Independent activation of CREB3L2 by glucose fills a regulatory gap in mouse β-cells by co-ordinating insulin biosynthesis with secretory granule formation. Mol Metab 2024; 79:101845. [PMID: 38013154 PMCID: PMC10755490 DOI: 10.1016/j.molmet.2023.101845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 11/22/2023] [Accepted: 11/23/2023] [Indexed: 11/29/2023] Open
Abstract
OBJECTIVE Although individual steps have been characterized, there is little understanding of the overall process whereby glucose co-ordinates the biosynthesis of insulin with its export out of the endoplasmic reticulum (ER) and incorporation into insulin secretory granules (ISGs). Here we investigate a role for the transcription factor CREB3L2 in this context. METHODS MIN6 cells and mouse islets were analysed by immunoblotting after treatment with glucose, fatty acids, thapsigargin and various inhibitors. Knockdown of CREB3L2 was achieved using si or sh constructs by transfection, or viral delivery. In vivo metabolic phenotyping was conducted after deletion of CREB3L2 in β-cells of adult mice using Ins1-CreER+. Islets were isolated for RNAseq and assays of glucose-stimulated insulin secretion (GSIS). Trafficking was monitored in islet monolayers using a GFP-tagged proinsulin construct that allows for synchronised release from the ER. RESULTS With a Km ≈3.5 mM, glucose rapidly (T1/2 0.9 h) increased full length (FL) CREB3L2 followed by a slower rise (T1/2 2.5 h) in its transcriptionally-active cleavage product, P60 CREB3L2. Glucose stimulation repressed the ER stress marker, CHOP, and this was partially reverted by knockdown of CREB3L2. Activation of CREB3L2 by glucose was not due to ER stress, however, but a combination of O-GlcNAcylation, which impaired proteasomal degradation of FL-CREB3L2, and mTORC1 stimulation, which enhanced its conversion to P60. cAMP generation also activated CREB3L2, but independently of glucose. Deletion of CREB3L2 inhibited GSIS ex vivo and, following a high-fat diet (HFD), impaired glucose tolerance and insulin secretion in vivo. RNAseq revealed that CREB3L2 regulated genes controlling trafficking to-and-from the Golgi, as well as a broader cohort associated with β-cell compensation during a HFD. Although post-Golgi trafficking appeared intact, knockdown of CREB3L2 impaired the generation of both nascent ISGs and proinsulin condensates in the Golgi, implying a defect in ER export of proinsulin and/or its processing in the Golgi. CONCLUSION The stimulation of CREB3L2 by glucose defines a novel, rapid and direct mechanism for co-ordinating the synthesis, packaging and storage of insulin, thereby minimizing ER overload and optimizing β-cell function under conditions of high secretory demand. Upregulation of CREB3L2 also potentially contributes to the benefits of GLP1 agonism and might in itself constitute a novel means of treating β-cell failure.
Collapse
Affiliation(s)
- Nancy Sue
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW 2010, Australia
| | - Le May Thai
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW 2010, Australia
| | - Atsushi Saito
- Department of Biochemistry, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Cierra K Boyer
- Fraternal Order of Eagles Diabetes Research Center, Department of Internal Medicine, University of Iowa, Iowa City, IA 52246, USA
| | - Ashleigh M Fordham
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW 2010, Australia
| | - Chenxu Yan
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW 2010, Australia
| | - Aimee Davenport
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW 2010, Australia
| | - Jiang Tao
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW 2010, Australia
| | - Mohammed Bensellam
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW 2010, Australia
| | - James Cantley
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW 2010, Australia
| | - Yan-Chuan Shi
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW 2010, Australia; St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, Australia
| | - Samuel B Stephens
- Fraternal Order of Eagles Diabetes Research Center, Department of Internal Medicine, University of Iowa, Iowa City, IA 52246, USA
| | - Kazunori Imaizumi
- Department of Biochemistry, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Trevor J Biden
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW 2010, Australia; St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Sydney, Australia.
| |
Collapse
|
4
|
Perrier J, Nawrot M, Madec AM, Chikh K, Chauvin MA, Damblon C, Sabatier J, Thivolet CH, Rieusset J, Rautureau GJP, Panthu B. Human Pancreatic Islets React to Glucolipotoxicity by Secreting Pyruvate and Citrate. Nutrients 2023; 15:4791. [PMID: 38004183 PMCID: PMC10674605 DOI: 10.3390/nu15224791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 11/07/2023] [Accepted: 11/10/2023] [Indexed: 11/26/2023] Open
Abstract
Progressive decline in pancreatic beta-cell function is central to the pathogenesis of type 2 diabetes (T2D). Here, we explore the relationship between the beta cell and its nutritional environment, asking how an excess of energy substrate leads to altered energy production and subsequent insulin secretion. Alterations in intracellular metabolic homeostasis are key markers of islets with T2D, but changes in cellular metabolite exchanges with their environment remain unknown. We answered this question using nuclear magnetic resonance-based quantitative metabolomics and evaluated the consumption or secretion of 31 extracellular metabolites from healthy and T2D human islets. Islets were also cultured under high levels of glucose and/or palmitate to induce gluco-, lipo-, and glucolipotoxicity. Biochemical analyses revealed drastic alterations in the pyruvate and citrate pathways, which appear to be associated with mitochondrial oxoglutarate dehydrogenase (OGDH) downregulation. We repeated these manipulations on the rat insulinoma-derived beta-pancreatic cell line (INS-1E). Our results highlight an OGDH downregulation with a clear effect on the pyruvate and citrate pathways. However, citrate is directed to lipogenesis in the INS-1E cells instead of being secreted as in human islets. Our results demonstrate the ability of metabolomic approaches performed on culture media to easily discriminate T2D from healthy and functional islets.
Collapse
Affiliation(s)
- Johan Perrier
- Laboratoire CarMeN, UMR INSERM U1060/INRAE U1397, University of Lyon, Université Claude Bernard Lyon 1, 69310 Pierre-Bénite, France
| | - Margaux Nawrot
- Laboratoire CarMeN, UMR INSERM U1060/INRAE U1397, University of Lyon, Université Claude Bernard Lyon 1, 69310 Pierre-Bénite, France
| | - Anne-Marie Madec
- Laboratoire CarMeN, UMR INSERM U1060/INRAE U1397, University of Lyon, Université Claude Bernard Lyon 1, 69310 Pierre-Bénite, France
| | - Karim Chikh
- Laboratoire CarMeN, UMR INSERM U1060/INRAE U1397, University of Lyon, Université Claude Bernard Lyon 1, 69310 Pierre-Bénite, France
- Department of Endocrinology and Diabetes, Hospices Civils de Lyon, Hopital Lyon Sud, 69310 Pierre-Bénite, France
| | - Marie-Agnès Chauvin
- Laboratoire CarMeN, UMR INSERM U1060/INRAE U1397, University of Lyon, Université Claude Bernard Lyon 1, 69310 Pierre-Bénite, France
| | - Christian Damblon
- Unité de Recherche MolSys, Faculté des Sciences, Université de Liège, 99131 Liège, Belgium
| | - Julia Sabatier
- Laboratory of Cell Therapy for Diabetes (LTCD), PRIMS Facility, Institute for Regenerative Medicine and Biotherapy (IRMB), University Hospital of Montpellier, 34295 Montpellier, France
| | - Charles H. Thivolet
- Laboratoire CarMeN, UMR INSERM U1060/INRAE U1397, University of Lyon, Université Claude Bernard Lyon 1, 69310 Pierre-Bénite, France
- Department of Endocrinology and Diabetes, Hospices Civils de Lyon, Hopital Lyon Sud, 69310 Pierre-Bénite, France
| | - Jennifer Rieusset
- Laboratoire CarMeN, UMR INSERM U1060/INRAE U1397, University of Lyon, Université Claude Bernard Lyon 1, 69310 Pierre-Bénite, France
| | - Gilles J. P. Rautureau
- Centre de Résonance Magnétique Nucléaire à Très Hauts Champs, UMR 5082 CNRS, ENS Lyon, UCBL, Université de Lyon, 69100 Villeurbanne, France
| | - Baptiste Panthu
- Laboratoire CarMeN, UMR INSERM U1060/INRAE U1397, University of Lyon, Université Claude Bernard Lyon 1, 69310 Pierre-Bénite, France
| |
Collapse
|
5
|
Hossain MM, Roat R, Christopherson J, Free C, Ansarullah, James B, Guo Z. Exploring lncRNAs associated with human pancreatic islet cell death induced by transfer of adoptive lymphocytes in a humanized mouse model. Front Endocrinol (Lausanne) 2023; 14:1244688. [PMID: 38027148 PMCID: PMC10646418 DOI: 10.3389/fendo.2023.1244688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 09/29/2023] [Indexed: 12/01/2023] Open
Abstract
Background Long noncoding RNA (lncRNA)-mediated posttranscriptional and epigenetic landscapes of gene regulation are associated with numerous human diseases. However, the regulatory mechanisms governing human β-cell function and survival remain unknown. Owing to technical and ethical constraints, studying the direct role of lncRNAs in β-cell function and survival in humans in vivo is difficult. Therefore, we utilized humanized mice with human islets to investigate lncRNA expression using whole transcriptome shotgun sequencing. Our study aimed to characterize lncRNAs that may be crucial for human islet cell function and survival. Methods Human β-cell death was induced in humanized mice engrafted with functional human islets. Using these humanized mice harboring human islets with induced β-cell death, we investigated lncRNA expression through whole transcriptome shotgun sequencing. Additionally, we systematically identified, characterized, and explored the regulatory functions of lncRNAs that are potentially important for human pancreatic islet cell function and survival. Results Human islet cell death was induced in humanized mice engrafted with functional human islets. RNA sequencing analysis of isolated human islets, islet grafts from humanized mice with and without induced cell death, revealed aberrant expression of a distinct set of lncRNAs that are associated with the deregulated mRNAs important for cellular processes and molecular pathways related to β-cell function and survival. A total of 10 lncRNA isoforms (SCYL1-1:22, POLG2-1:1, CTRB1-1:1, SRPK1-1:1, GTF3C5-1:1, PPY-1:1, CTRB1-1:5, CPA5-1:1, BCAR1-2:1, and CTRB1-1:4) were identified as highly enriched and specific to human islets. These lncRNAs were deregulated in human islets from donors with different BMIs and with type 2 diabetes (T2D), as well as in cultured human islets with glucose stimulation and induced cell death induced by cytokines. Aberrant expression of these lncRNAs was detected in the exosomes from the medium used to culture islets with cytokines. Conclusion Islet-enriched and specific human lncRNAs are deregulated in human islet grafts and cultured human islets with induced cell death. These lncRNAs may be crucial for human β-cell function and survival and could have an impact on identifying biomarkers for β-cell loss and discovering novel therapeutic targets to enhance β-cell function and survival.
Collapse
Affiliation(s)
- Md Munir Hossain
- The Sanford Project/Children Health Research Center, Sanford Research, Sioux Falls, SD, United States
- Department of Animal Breeding and Genetics, Bangladesh Agricultural University, Mymensingh, Bangladesh
| | - Regan Roat
- The Sanford Project/Children Health Research Center, Sanford Research, Sioux Falls, SD, United States
| | - Jenica Christopherson
- The Sanford Project/Children Health Research Center, Sanford Research, Sioux Falls, SD, United States
| | - Colette Free
- The Sanford Project/Children Health Research Center, Sanford Research, Sioux Falls, SD, United States
| | - Ansarullah
- The Sanford Project/Children Health Research Center, Sanford Research, Sioux Falls, SD, United States
| | - Brian James
- The Sanford Project/Children Health Research Center, Sanford Research, Sioux Falls, SD, United States
- Discovery Genomics, Inc., Irvine, CA, United States
| | - Zhiguang Guo
- The Sanford Project/Children Health Research Center, Sanford Research, Sioux Falls, SD, United States
| |
Collapse
|
6
|
Lin D, Yu J, Lin L, Ou Q, Quan H. MRPS6 modulates glucose-stimulated insulin secretion in mouse islet cells through mitochondrial unfolded protein response. Sci Rep 2023; 13:16173. [PMID: 37758822 PMCID: PMC10533529 DOI: 10.1038/s41598-023-43438-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 09/24/2023] [Indexed: 09/29/2023] Open
Abstract
Lack of efficient insulin secretion from the pancreas can lead to impaired glucose tolerance (IGT), prediabetes, and diabetes. We have previously identified two IGT-associated single nucleotide polymorphisms (SNPs) rs62212118 and rs13052524 located at two overlapping genes: MRPS6 and SLC5A3. In this study, we show that MRPS6 but not SLC5A3 regulates glucose-stimulated insulin secretion (GSIS) in primary human β-cell and a mouse pancreatic insulinoma β-cell line. Data mining and biochemical studies reveal that MRPS6 is positively regulated by the mitochondrial unfolded protein response (UPRmt), but feedback inhibits UPRmt. Disruption of such feedback by MRPS6 knockdown causes UPRmt hyperactivation in high glucose conditions, hence elevated ROS levels, increased apoptosis, and impaired GSIS. Conversely, MRPS6 overexpression reduces UPRmt, mitigates high glucose-induced ROS levels and apoptosis, and enhances GSIS in an ATF5-dependent manner. Consistently, UPRmt up-regulation or down-regulation by modulating ATF5 expression is sufficient to decrease or increase GSIS. The negative role of UPRmt in GSIS is further supported by analysis of public transcriptomic data from murine islets. In all, our studies identify MRPS6 and UPRmt as novel modulators of GSIS and apoptosis in β-cells, contributing to our understanding of the molecular and cellular mechanisms of IGT, prediabetes, and diabetes.
Collapse
Affiliation(s)
- Danhong Lin
- Department of Endocrinology, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, No.19 Xiuhua Road, Haikou, 570311, Hainan, China
| | - Jingwen Yu
- Department of Endocrinology, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, No.19 Xiuhua Road, Haikou, 570311, Hainan, China
| | - Leweihua Lin
- Department of Endocrinology, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, No.19 Xiuhua Road, Haikou, 570311, Hainan, China
| | - Qianying Ou
- Department of Endocrinology, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, No.19 Xiuhua Road, Haikou, 570311, Hainan, China
| | - Huibiao Quan
- Department of Endocrinology, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, No.19 Xiuhua Road, Haikou, 570311, Hainan, China.
| |
Collapse
|
7
|
Oberhauser L, Jiménez-Sánchez C, Madsen JGS, Duhamel D, Mandrup S, Brun T, Maechler P. Glucolipotoxicity promotes the capacity of the glycerolipid/NEFA cycle supporting the secretory response of pancreatic beta cells. Diabetologia 2022; 65:705-720. [PMID: 35018486 DOI: 10.1007/s00125-021-05633-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Accepted: 10/12/2021] [Indexed: 11/03/2022]
Abstract
AIMS/HYPOTHESIS Chronic exposure of pancreatic beta cells to high glucose and fatty acids has been proposed to induce glucolipotoxicity. However, contradictory results suggest adaptations of the beta cells, which might be instrumental for partial preservation of the secretory response. In this context, we delineated the expression pattern of genes related to lipid pathways along with fat storage/mobilisation during glucose-stimulated insulin secretion. METHODS Insulin-secreting cells were cultured for 3 days at different glucose concentrations (5.5, 11.1, 25 mmol/l) without or with BSA-complexed 0.4 mmol/l palmitate and oleate. Then, transcriptomic analyses of lipid pathways were performed in human islets by RNA-Seq and in INS-1E cells and rat islets by quantitative RT-PCR. Storage of fat was assessed in INS-1E cells by electron microscopy and Bodipy staining, which was also used for measuring lipid mobilisation rate. The secretory response was monitored during acute 15 mmol/l glucose stimulation using online luminescence assay for INS-1E cells and by radioimmunoassay for rat islets. RESULTS In human islets, chronic exposure to palmitate and oleate modified expression of a panel of genes involved in lipid handling. Culture at 25 mmol/l glucose upregulated genes encoding for enzymes of the glycerolipid/NEFA cycle and downregulated receptors implicated in fatty acid signalling. Similar results were obtained in INS-1E cells, indicating enhanced capacity of the glycerolipid/NEFA cycle under glucotoxic conditions. Exposure to unsaturated C18:1 fatty acid favoured intracellular lipid accumulation in a glucose-dependent way, an effect also observed with saturated C16:0 fatty acid when combined with the panlipase inhibitor Orlistat. After the glucolipotoxic culture, intracellular fat mobilisation was required for acute glucose-stimulated secretion, particularly in oleate-treated cells under glucotoxic culture conditions. The lipid mobilisation rate was governed chiefly by the levels of stored fat as a direct consequence of the culture conditions rather than energetic demands, except in palmitate-loaded cells. CONCLUSIONS/INTERPRETATION Glucolipotoxic conditions promote the capacity of the glycerolipid/NEFA cycle thereby preserving part of the secretory response. The cycle of fat storage/mobilisation emerges as a mechanism helping the beta cell to cope with glucotoxic conditions.
Collapse
Affiliation(s)
- Lucie Oberhauser
- Department of Cell Physiology and Metabolism, University of Geneva Medical Center, Geneva, Switzerland
- Faculty Diabetes Center, University of Geneva Medical Center, Geneva, Switzerland
| | - Cecilia Jiménez-Sánchez
- Department of Cell Physiology and Metabolism, University of Geneva Medical Center, Geneva, Switzerland
- Faculty Diabetes Center, University of Geneva Medical Center, Geneva, Switzerland
| | - Jesper Grud Skat Madsen
- Functional Genomics and Metabolism Research Unit, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Dominique Duhamel
- Department of Cell Physiology and Metabolism, University of Geneva Medical Center, Geneva, Switzerland
- Faculty Diabetes Center, University of Geneva Medical Center, Geneva, Switzerland
| | - Susanne Mandrup
- Functional Genomics and Metabolism Research Unit, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Thierry Brun
- Department of Cell Physiology and Metabolism, University of Geneva Medical Center, Geneva, Switzerland
- Faculty Diabetes Center, University of Geneva Medical Center, Geneva, Switzerland
| | - Pierre Maechler
- Department of Cell Physiology and Metabolism, University of Geneva Medical Center, Geneva, Switzerland.
- Faculty Diabetes Center, University of Geneva Medical Center, Geneva, Switzerland.
| |
Collapse
|
8
|
Chan JY, Bensellam M, Lin RCY, Liang C, Lee K, Jonas JC, Laybutt DR. Transcriptome analysis of islets from diabetes-resistant and diabetes-prone obese mice reveals novel gene regulatory networks involved in beta-cell compensation and failure. FASEB J 2021; 35:e21608. [PMID: 33977593 DOI: 10.1096/fj.202100009r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 03/23/2021] [Accepted: 04/05/2021] [Indexed: 01/02/2023]
Abstract
The mechanisms underpinning beta-cell compensation for obesity-associated insulin resistance and beta-cell failure in type 2 diabetes remain poorly understood. We used a large-scale strategy to determine the time-dependent transcriptomic changes in islets of diabetes-prone db/db and diabetes-resistant ob/ob mice at 6 and 16 weeks of age. Differentially expressed genes were subjected to cluster, gene ontology, pathway and gene set enrichment analyses. A distinctive gene expression pattern was observed in 16 week db/db islets in comparison to the other groups with alterations in transcriptional regulators of islet cell identity, upregulation of glucose/lipid metabolism, and various stress response genes, and downregulation of specific amino acid transport and metabolism genes. In contrast, ob/ob islets displayed a coordinated downregulation of metabolic and stress response genes at 6 weeks of age, suggestive of a preemptive reconfiguration in these islets to lower the threshold of metabolic activation in response to increased insulin demand thereby preserving beta-cell function and preventing cellular stress. In addition, amino acid transport and metabolism genes were upregulated in ob/ob islets, suggesting an important role of glutamate metabolism in beta-cell compensation. Gene set enrichment analysis of differentially expressed genes identified the enrichment of binding motifs for transcription factors, FOXO4, NFATC1, and MAZ. siRNA-mediated knockdown of these genes in MIN6 cells altered cell death, insulin secretion, and stress gene expression. In conclusion, these data revealed novel gene regulatory networks involved in beta-cell compensation and failure. Preemptive metabolic reconfiguration in diabetes-resistant islets may dampen metabolic activation and cellular stress during obesity.
Collapse
Affiliation(s)
- Jeng Yie Chan
- Garvan Institute of Medical Research, Sydney, NSW, Australia.,School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Mohammed Bensellam
- Garvan Institute of Medical Research, Sydney, NSW, Australia.,Pôle D'endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
| | - Ruby C Y Lin
- School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.,Centre for Infectious Diseases and Microbiology, Westmead Institute for Medical Research, Sydney, NSW, Australia.,Sydney Medical School, The University of Sydney, Sydney, NSW, Australia
| | - Cassandra Liang
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Kailun Lee
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Jean-Christophe Jonas
- Pôle D'endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
| | - D Ross Laybutt
- Garvan Institute of Medical Research, Sydney, NSW, Australia.,School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
| |
Collapse
|
9
|
Benáková Š, Holendová B, Plecitá-Hlavatá L. Redox Homeostasis in Pancreatic β-Cells: From Development to Failure. Antioxidants (Basel) 2021; 10:antiox10040526. [PMID: 33801681 PMCID: PMC8065646 DOI: 10.3390/antiox10040526] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/23/2021] [Accepted: 03/25/2021] [Indexed: 12/16/2022] Open
Abstract
Redox status is a key determinant in the fate of β-cell. These cells are not primarily detoxifying and thus do not possess extensive antioxidant defense machinery. However, they show a wide range of redox regulating proteins, such as peroxiredoxins, thioredoxins or thioredoxin reductases, etc., being functionally compartmentalized within the cells. They keep fragile redox homeostasis and serve as messengers and amplifiers of redox signaling. β-cells require proper redox signaling already in cell ontogenesis during the development of mature β-cells from their progenitors. We bring details about redox-regulated signaling pathways and transcription factors being essential for proper differentiation and maturation of functional β-cells and their proliferation and insulin expression/maturation. We briefly highlight the targets of redox signaling in the insulin secretory pathway and focus more on possible targets of extracellular redox signaling through secreted thioredoxin1 and thioredoxin reductase1. Tuned redox homeostasis can switch upon chronic pathological insults towards the dysfunction of β-cells and to glucose intolerance. These are characteristics of type 2 diabetes, which is often linked to chronic nutritional overload being nowadays a pandemic feature of lifestyle. Overcharged β-cell metabolism causes pressure on proteostasis in the endoplasmic reticulum, mainly due to increased demand on insulin synthesis, which establishes unfolded protein response and insulin misfolding along with excessive hydrogen peroxide production. This together with redox dysbalance in cytoplasm and mitochondria due to enhanced nutritional pressure impact β-cell redox homeostasis and establish prooxidative metabolism. This can further affect β-cell communication in pancreatic islets through gap junctions. In parallel, peripheral tissues losing insulin sensitivity and overall impairment of glucose tolerance and gut microbiota establish local proinflammatory signaling and later systemic metainflammation, i.e., low chronic inflammation prooxidative properties, which target β-cells leading to their dedifferentiation, dysfunction and eventually cell death.
Collapse
Affiliation(s)
- Štěpánka Benáková
- Department of Mitochondrial Physiology, Institute of Physiology, Czech Academy of Sciences, 142 20 Prague 4, Czech Republic; (Š.B.); (B.H.)
- First Faculty of Medicine, Charles University, Katerinska 1660/32, 121 08 Prague, Czech Republic
| | - Blanka Holendová
- Department of Mitochondrial Physiology, Institute of Physiology, Czech Academy of Sciences, 142 20 Prague 4, Czech Republic; (Š.B.); (B.H.)
| | - Lydie Plecitá-Hlavatá
- Department of Mitochondrial Physiology, Institute of Physiology, Czech Academy of Sciences, 142 20 Prague 4, Czech Republic; (Š.B.); (B.H.)
- Department of Mitochondrial Physiology, Czech Academy of Sciences, Videnska 1083, 142 20 Prague 4, Czech Republic
- Correspondence: ; Tel.: +420-296-442-285
| |
Collapse
|
10
|
Emerging Roles of Metallothioneins in Beta Cell Pathophysiology: Beyond and Above Metal Homeostasis and Antioxidant Response. BIOLOGY 2021; 10:biology10030176. [PMID: 33652748 PMCID: PMC7996892 DOI: 10.3390/biology10030176] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/17/2021] [Accepted: 02/22/2021] [Indexed: 12/15/2022]
Abstract
Simple Summary Defective insulin secretion by pancreatic beta cells is key for the development of type 2 diabetes but the precise mechanisms involved are poorly understood. Metallothioneins are metal binding proteins whose precise biological roles have not been fully characterized. Available evidence indicated that Metallothioneins are protective cellular effectors involved in heavy metal detoxification, metal ion homeostasis and antioxidant defense. This concept has however been challenged by emerging evidence in different medical research fields revealing novel negative roles of Metallothioneins, including in the context of diabetes. In this review, we gather and analyze the available knowledge regarding the complex roles of Metallothioneins in pancreatic beta cell biology and insulin secretion. We comprehensively analyze the evidence showing positive effects of Metallothioneins on beta cell function and survival as well as the emerging evidence revealing negative effects and discuss the possible underlying mechanisms. We expose in parallel findings from other medical research fields and underscore unsettled questions. Then, we propose some future research directions to improve knowledge in the field. Abstract Metallothioneins (MTs) are low molecular weight, cysteine-rich, metal-binding proteins whose precise biological roles have not been fully characterized. Existing evidence implicated MTs in heavy metal detoxification, metal ion homeostasis and antioxidant defense. MTs were thus categorized as protective effectors that contribute to cellular homeostasis and survival. This view has, however, been challenged by emerging evidence in different medical fields revealing novel pathophysiological roles of MTs, including inflammatory bowel disease, neurodegenerative disorders, carcinogenesis and diabetes. In the present focused review, we discuss the evidence for the role of MTs in pancreatic beta-cell biology and insulin secretion. We highlight the pattern of specific isoforms of MT gene expression in rodents and human beta-cells. We then discuss the mechanisms involved in the regulation of MTs in islets under physiological and pathological conditions, particularly type 2 diabetes, and analyze the evidence revealing adaptive and negative roles of MTs in beta-cells and the potential mechanisms involved. Finally, we underscore the unsettled questions in the field and propose some future research directions.
Collapse
|
11
|
Rosselot C, Baumel-Alterzon S, Li Y, Brill G, Lambertini L, Katz LS, Lu G, Garcia-Ocaña A, Scott DK. The many lives of Myc in the pancreatic β-cell. J Biol Chem 2021; 296:100122. [PMID: 33239359 PMCID: PMC7949031 DOI: 10.1074/jbc.rev120.011149] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 11/20/2020] [Accepted: 11/25/2020] [Indexed: 12/19/2022] Open
Abstract
Diabetes results from insufficient numbers of functional pancreatic β-cells. Thus, increasing the number of available functional β-cells ex vivo for transplantation, or regenerating them in situ in diabetic patients, is a major focus of diabetes research. The transcription factor, Myc, discovered decades ago lies at the nexus of most, if not all, known proliferative pathways. Based on this, many studies in the 1990s and early 2000s explored the potential of harnessing Myc expression to expand β-cells for diabetes treatment. Nearly all these studies in β-cells used pathophysiological or supraphysiological levels of Myc and reported enhanced β-cell death, dedifferentiation, or the formation of insulinomas if cooverexpressed with Bcl-xL, an inhibitor of apoptosis. This obviously reduced the enthusiasm for Myc as a therapeutic target for β-cell regeneration. However, recent studies indicate that "gentle" induction of Myc expression enhances β-cell replication without induction of cell death or loss of insulin secretion, suggesting that appropriate levels of Myc could have therapeutic potential for β-cell regeneration. Furthermore, although it has been known for decades that Myc is induced by glucose in β-cells, very little is known about how this essential anabolic transcription factor perceives and responds to nutrients and increased insulin demand in vivo. Here we summarize the previous and recent knowledge of Myc in the β-cell, its potential for β-cell regeneration, and its physiological importance for neonatal and adaptive β-cell expansion.
Collapse
Affiliation(s)
- Carolina Rosselot
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Sharon Baumel-Alterzon
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Yansui Li
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Gabriel Brill
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Luca Lambertini
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Liora S Katz
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Geming Lu
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Adolfo Garcia-Ocaña
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA.
| | - Donald K Scott
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| |
Collapse
|
12
|
Maachi H, Fergusson G, Ethier M, Brill GN, Katz LS, Honig LB, Metukuri MR, Scott DK, Ghislain J, Poitout V. HB-EGF Signaling Is Required for Glucose-Induced Pancreatic β-Cell Proliferation in Rats. Diabetes 2020; 69:369-380. [PMID: 31882563 PMCID: PMC7034189 DOI: 10.2337/db19-0643] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 12/19/2019] [Indexed: 12/19/2022]
Abstract
The molecular mechanisms of β-cell compensation to metabolic stress are poorly understood. We previously observed that nutrient-induced β-cell proliferation in rats is dependent on epidermal growth factor receptor (EGFR) signaling. The aim of this study was to determine the role of the EGFR ligand heparin-binding EGF-like growth factor (HB-EGF) in the β-cell proliferative response to glucose, a β-cell mitogen and key regulator of β-cell mass in response to increased insulin demand. We show that exposure of isolated rat and human islets to HB-EGF stimulates β-cell proliferation. In rat islets, inhibition of EGFR or HB-EGF blocks the proliferative response not only to HB-EGF but also to glucose. Furthermore, knockdown of HB-EGF in rat islets blocks β-cell proliferation in response to glucose ex vivo and in vivo in transplanted glucose-infused rats. Mechanistically, we demonstrate that HB-EGF mRNA levels are increased in β-cells in response to glucose in a carbohydrate-response element-binding protein (ChREBP)-dependent manner. In addition, chromatin immunoprecipitation studies identified ChREBP binding sites in proximity to the HB-EGF gene. Finally, inhibition of Src family kinases, known to be involved in HB-EGF processing, abrogated glucose-induced β-cell proliferation. Our findings identify a novel glucose/HB-EGF/EGFR axis implicated in β-cell compensation to increased metabolic demand.
Collapse
Affiliation(s)
- Hasna Maachi
- Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
- Department of Pharmacology and Physiology, University of Montreal, Montreal, Quebec, Canada
| | - Grace Fergusson
- Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
| | - Melanie Ethier
- Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
| | - Gabriel N Brill
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Liora S Katz
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Lee B Honig
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | | | - Donald K Scott
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Julien Ghislain
- Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
| | - Vincent Poitout
- Montreal Diabetes Research Center, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
- Department of Medicine, University of Montreal, Montreal, Quebec, Canada
| |
Collapse
|
13
|
Moens C, Bensellam M, Himpe E, Muller CJF, Jonas JC, Bouwens L. Aspalathin Protects Insulin-Producing β Cells against Glucotoxicity and Oxidative Stress-Induced Cell Death. Mol Nutr Food Res 2020; 64:e1901009. [PMID: 32012427 DOI: 10.1002/mnfr.201901009] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 12/23/2019] [Indexed: 12/17/2022]
Abstract
SCOPE Aspalathin, the main polyphenolic phytochemical of rooibos (Aspalathus linearis), has been attributed with health promoting properties, including a glucose lowering effect that can prove interesting for application as nutraceutical or therapeutic in (pre-)diabetics. Preservation of β cell mass in the pancreas is considered a key issue for diabetes prevention or treatment, therefore the aim is to investigate whether aspalathin also has β cell cytoprotective potential. METHODS AND RESULTS Rat pancreatic islets and the β cell line Insulinoma 1E (INS1E) are studied in vitro after exposure to various cytotoxic agents, namely streptozotocin (STZ), hydrogen peroxide, or chronic high glucose. The effect of aspalathin on cell survival and apoptosis is studied. Expression of relevant cytoprotective genes is analyzed by qRT-PCR and proteins by Western blot. Aspalathin is found to protect β cells against cytotoxicity and apoptosis. This is associated with increased translocation of nuclear factor erythroid 2-related factor 2 (NRF2) and expression of its antioxidant target genes heme oxygenase 1 (Hmox1), NAD(P)H quinone dehydrogenase 1 (Nqo-1), and superoxide dismutase 1 (Sod1). CONCLUSION It is proposed that aspalathin protects β cells against glucotoxicity and oxidative stress by increasing the expression of NRF2-regulated antioxidant enzymes. This indicates that aspalathin is an interesting β cell cytoprotectant.
Collapse
Affiliation(s)
- Céline Moens
- Cell Differentiation Lab, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Jette, Brussels, Belgium
| | - Mohammed Bensellam
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Avenue Hippocrate 55, 1200 Brussels, Brussels, Belgium
| | - Eddy Himpe
- Cell Differentiation Lab, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Jette, Brussels, Belgium
| | - Christo J F Muller
- Biomedical Research and Innovation Platform, South African Medical Research Council, Francie van Zijl Drive, 7505, Western Cape, Tygerberg, South Africa
| | - Jean-Christophe Jonas
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Avenue Hippocrate 55, 1200 Brussels, Brussels, Belgium
| | - Luc Bouwens
- Cell Differentiation Lab, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Jette, Brussels, Belgium
| |
Collapse
|
14
|
Carter S, Solomon TPJ. Exercise-Induced Improvements in Postprandial Glucose Response Are Blunted by Pre-Exercise Hyperglycemia: A Randomized Crossover Trial in Healthy Individuals. Front Endocrinol (Lausanne) 2020; 11:566548. [PMID: 33178135 PMCID: PMC7593662 DOI: 10.3389/fendo.2020.566548] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 09/15/2020] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Exercise improves glycemic control but the magnitude, and in some cases, the direction of this effect is variable. Ambient hyperglycemia has been implicated in this exercise response heterogeneity. The current study investigated whether pre-exercise hyperglycemia directly impacts the effect of exercise on glycemic control. METHODS Twelve healthy normal glucose-tolerant males completed four trials in a randomized, crossover design. Each trial consisted of 24-h pre-intervention monitoring, a 7-h intervention, and 24-h post-intervention monitoring. Glycemic control was measured throughout the study by continuous glucose monitoring. The four interventions were no exercise (CON) or 45 min of cycling exercise (70%HRmax) preceded by 3.5 h of either normoglycemia (NG-Ex), steady-state hyperglycemia induced by constant glucose infusion (HG-Ex) or fluctuating glycemia induced by repeated glucose bolus infusions (FG-Ex). RESULTS Physical activity and diet were similar between trials, and energy expenditure during exercise was matched between exercise trials (all P > 0.05). Mean glucose during the 3.5 h ± infusion period was higher in HG-Ex (mean ± SEM; 7.2 ± 0.4 mmol/L) and FG-Ex (7.3 ± 0.3 mmol/L) compared to CON (4.8 ± 0.2 mmol/L) and NG-Ex (5.0 ± 0.2 mmol/L) trials (P < 0.01). Glycemic variability was greatest in FG-Ex (P < 0.01). Following the interventions, the postprandial glucose response (iAUC) was reduced by exercise in NG-Ex compared to CON (321.1 ± 38.6 vs. 445.5 ± 49.7 mmol/L.8h, P < 0.05, d=0.81). This benefit was blunted when exercise was preceded by steady-state (HG-Ex, 425.3 ± 45.7 mmol/L.8h) and fluctuating (FG-Ex, 465.5 ± 39.3 mmol/L.8h) hyperglycemia (both P > 0.05 vs. CON). CONCLUSION Pre-exercise hyperglycemia blunted the glucoregulatory benefits of acute exercise upon postprandial glucose response, suggesting that exposure to hyperglycemia contributes to exercise response heterogeneity. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov, identifier NCT03284216.
Collapse
Affiliation(s)
- Steven Carter
- School of Sport, Exercise, and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, United Kingdom
- *Correspondence: Steven Carter,
| | - Thomas P. J. Solomon
- School of Sport, Exercise, and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, United Kingdom
- Institute of Systems and Metabolism Research, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, United Kingdom
| |
Collapse
|
15
|
Bensellam M, Shi YC, Chan JY, Laybutt DR, Chae H, Abou-Samra M, Pappas EG, Thomas HE, Gilon P, Jonas JC. Metallothionein 1 negatively regulates glucose-stimulated insulin secretion and is differentially expressed in conditions of beta cell compensation and failure in mice and humans. Diabetologia 2019; 62:2273-2286. [PMID: 31624901 DOI: 10.1007/s00125-019-05008-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 08/13/2019] [Indexed: 10/25/2022]
Abstract
AIMS/HYPOTHESIS The mechanisms responsible for beta cell compensation in obesity and for beta cell failure in type 2 diabetes are poorly defined. The mRNA levels of several metallothionein (MT) genes are upregulated in islets from individuals with type 2 diabetes, but their role in beta cells is not clear. Here we examined: (1) the temporal changes of islet Mt1 and Mt2 gene expression in mouse models of beta cell compensation and failure; and (2) the role of Mt1 and Mt2 in beta cell function and glucose homeostasis in mice. METHODS Mt1 and Mt2 expression was assessed in islets from: (1) control lean (chow diet-fed) and diet-induced obese (high-fat diet-fed for 6 weeks) mice; (2) mouse models of diabetes (db/db mice) at 6 weeks old (prediabetes) and 16 weeks old (after diabetes onset) and age-matched db/+ (control) mice; and (3) obese non-diabetic ob/ob mice (16-week-old) and age-matched ob/+ (control) mice. MT1E, MT1X and MT2A expression was assessed in islets from humans with and without type 2 diabetes. Mt1-Mt2 double-knockout (KO) mice, transgenic mice overexpressing Mt1 under the control of its natural promoter (Tg-Mt1) and corresponding control mice were also studied. In MIN6 cells, MT1 and MT2 were inhibited by small interfering RNAs. mRNA levels were assessed by real-time RT-PCR, plasma insulin and islet MT levels by ELISA, glucose tolerance by i.p. glucose tolerance tests and overnight fasting-1 h refeeding tests, insulin tolerance by i.p. insulin tolerance tests, insulin secretion by RIA, cytosolic free Ca2+ concentration with Fura-2 leakage resistant (Fura-2 LR), cytosolic free Zn2+ concentration with Fluozin-3, and NAD(P)H by autofluorescence. RESULTS Mt1 and Mt2 mRNA levels were reduced in islets of murine models of beta cell compensation, whereas they were increased in diabetic db/db mice. In humans, MT1X mRNA levels were significantly upregulated in islets from individuals with type 2 diabetes in comparison with non-diabetic donors, while MT1E and MT2A mRNA levels were unchanged. Ex vivo, islet Mt1 and Mt2 mRNA and MT1 and MT2 protein levels were downregulated after culture with glucose at 10-30 mmol/l vs 2-5 mmol/l, in association with increased insulin secretion. In human islets, mRNA levels of MT1E, MT1X and MT2A were downregulated by stimulation with physiological and supraphysiological levels of glucose. In comparison with wild-type (WT) mice, Mt1-Mt2 double-KO mice displayed improved glucose tolerance in association with increased insulin levels and enhanced insulin release from isolated islets. In contrast, isolated islets from Tg-Mt1 mice displayed impaired glucose-stimulated insulin secretion (GSIS). In both Mt1-Mt2 double-KO and Tg-Mt1 models, the changes in GSIS occurred despite similar islet insulin content, rises in cytosolic free Ca2+ concentration and NAD(P)H levels, or intracellular Zn2+ concentration vs WT mice. In MIN6 cells, knockdown of MT1 but not MT2 potentiated GSIS, suggesting that Mt1 rather than Mt2 affects beta cell function. CONCLUSIONS/INTERPRETATION These findings implicate Mt1 as a negative regulator of insulin secretion. The downregulation of Mt1 is associated with beta cell compensation in obesity, whereas increased Mt1 accompanies beta cell failure and type 2 diabetes.
Collapse
Affiliation(s)
- Mohammed Bensellam
- Pôle d'endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Avenue Hippocrate 55 - B1.55.06, B-1200, Brussels, Belgium.
| | - Yan-Chuan Shi
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, UNSW Sydney, Sydney, New South Wales, Australia
| | - Jeng Yie Chan
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, UNSW Sydney, Sydney, New South Wales, Australia
| | - D Ross Laybutt
- Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- St Vincent's Clinical School, UNSW Sydney, Sydney, New South Wales, Australia
| | - Heeyoung Chae
- Pôle d'endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Avenue Hippocrate 55 - B1.55.06, B-1200, Brussels, Belgium
| | - Michel Abou-Samra
- Pôle d'endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Avenue Hippocrate 55 - B1.55.06, B-1200, Brussels, Belgium
| | - Evan G Pappas
- St Vincent's Institute, Department of Medicine, St Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Helen E Thomas
- St Vincent's Institute, Department of Medicine, St Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Patrick Gilon
- Pôle d'endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Avenue Hippocrate 55 - B1.55.06, B-1200, Brussels, Belgium
| | - Jean-Christophe Jonas
- Pôle d'endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Avenue Hippocrate 55 - B1.55.06, B-1200, Brussels, Belgium.
| |
Collapse
|
16
|
Roma LP, Jonas JC. Nutrient Metabolism, Subcellular Redox State, and Oxidative Stress in Pancreatic Islets and β-Cells. J Mol Biol 2019; 432:1461-1493. [PMID: 31634466 DOI: 10.1016/j.jmb.2019.10.012] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 09/25/2019] [Accepted: 10/10/2019] [Indexed: 01/01/2023]
Abstract
Insulin-secreting pancreatic β-cells play a critical role in blood glucose homeostasis and the development of type 2 diabetes (T2D) in the context of insulin resistance. Based on data obtained at the whole cell level using poorly specific chemical probes, reactive oxygen species (ROS) such as superoxide and hydrogen peroxide have been proposed to contribute to the stimulation of insulin secretion by nutrients (positive role) and to the alterations of cell survival and secretory function in T2D (negative role). This raised the controversial hypothesis that any attempt to decrease β-cell oxidative stress and apoptosis in T2D would further impair insulin secretion. Over the last decade, the development of genetically-encoded redox probes that can be targeted to cellular compartments of interest and are specific of redox couples allowed the evaluation of short- and long-term effects of nutrients on β-cell redox changes at the subcellular level. The data indicated that the nutrient regulation of β-cell redox signaling and ROS toxicity is far more complex than previously thought and that the subcellular compartmentation of these processes cannot be neglected when evaluating the mechanisms of ROS production or the efficacy of antioxidant enzymes and antioxidant drugs under glucolipotoxic conditions and in T2D. In this review, we present what is currently known about the compartmentation of redox homeostatic systems and tools to investigate it. We then review data about the effects of nutrients on β-cell subcellular redox state under normal conditions and in the context of T2D and discuss challenges and opportunities in the field.
Collapse
Affiliation(s)
- Leticia P Roma
- Universität des Saarlandes, Biophysics Department, Center for Human and Molecular Biology, Kirbergerstrasse Building 48, 66421, Homburg/Saar, Germany
| | - Jean-Christophe Jonas
- Université Catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Avenue Hippocrate 55 (B1.55.06), B-1200 Brussels, Belgium.
| |
Collapse
|
17
|
Ježek P, Jabůrek M, Plecitá-Hlavatá L. Contribution of Oxidative Stress and Impaired Biogenesis of Pancreatic β-Cells to Type 2 Diabetes. Antioxid Redox Signal 2019; 31:722-751. [PMID: 30450940 PMCID: PMC6708273 DOI: 10.1089/ars.2018.7656] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 11/05/2018] [Indexed: 12/14/2022]
Abstract
Significance: Type 2 diabetes development involves multiple changes in β-cells, related to the oxidative stress and impaired redox signaling, beginning frequently by sustained overfeeding due to the resulting lipotoxicity and glucotoxicity. Uncovering relationships among the dysregulated metabolism, impaired β-cell "well-being," biogenesis, or cross talk with peripheral insulin resistance is required for elucidation of type 2 diabetes etiology. Recent Advances: It has been recognized that the oxidative stress, lipotoxicity, and glucotoxicity cannot be separated from numerous other cell pathology events, such as the attempted compensation of β-cell for the increased insulin demand and dynamics of β-cell biogenesis and its "reversal" at dedifferentiation, that is, from the concomitantly decreasing islet β-cell mass (also due to transdifferentiation) and low-grade islet or systemic inflammation. Critical Issues: At prediabetes, the compensation responses of β-cells, attempting to delay the pathology progression-when exaggerated-set a new state, in which a self-checking redox signaling related to the expression of Ins gene expression is impaired. The resulting altered redox signaling, diminished insulin secretion responses to various secretagogues including glucose, may lead to excretion of cytokines or chemokines by β-cells or excretion of endosomes. They could substantiate putative stress signals to the periphery. Subsequent changes and lasting glucolipotoxicity promote islet inflammatory responses and further pathology spiral. Future Directions: Should bring an understanding of the β-cell self-checking and related redox signaling, including the putative stress signal to periphery. Strategies to cure or prevent type 2 diabetes could be based on the substitution of the "wrong" signal by the "correct" self-checking signal.
Collapse
Affiliation(s)
- Petr Ježek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Martin Jabůrek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Lydie Plecitá-Hlavatá
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| |
Collapse
|
18
|
Westermeier F, Holyoak T, Asenjo JL, Gatica R, Nualart F, Burbulis I, Bertinat R. Gluconeogenic Enzymes in β-Cells: Pharmacological Targets for Improving Insulin Secretion. Trends Endocrinol Metab 2019; 30:520-531. [PMID: 31213347 DOI: 10.1016/j.tem.2019.05.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/14/2019] [Accepted: 05/16/2019] [Indexed: 02/06/2023]
Abstract
Pancreatic β-cells express the gluconeogenic enzymes glucose 6-phosphatase (G6Pase), fructose 1,6-bisphosphatase (FBP), and phosphoenolpyruvate (PEP) carboxykinase (PCK), which modulate glucose-stimulated insulin secretion (GSIS) through their ability to reverse otherwise irreversible glycolytic steps. Here, we review current knowledge about the expression and regulation of these enzymes in the context of manipulating them to improve insulin secretion in diabetics. Because the regulation of gluconeogenic enzymes in β-cells is so poorly understood, we propose novel research avenues to study these enzymes as modulators of insulin secretion and β-cell dysfunction, with especial attention to FBP, which constitutes an attractive target with an inhibitor under clinical evaluation at present.
Collapse
Affiliation(s)
- Francisco Westermeier
- FH JOANNEUM Gesellschaft mbH University of Applied Sciences, Institute of Biomedical Science, Eggenberger Allee 13, 8020 Graz, Austria
| | - Todd Holyoak
- Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Joel L Asenjo
- Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Independencia 631, 5110566 Valdivia, Chile
| | - Rodrigo Gatica
- Escuela de Veterinaria, Facultad de Ciencias, Universidad Mayor, La Pirámide 5750, 8580745 Santiago, Chile
| | - Francisco Nualart
- Centro de Microscopía Avanzada, CMA BIO, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160 C, 4030000 Concepción, Chile
| | - Ian Burbulis
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Jordan Hall Room 6022, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA; Escuela de Medicina, Universidad San Sebastián, Sede Patagonia, Lago Panguipulli 1390, 5501842 Puerto Montt, Chile
| | - Romina Bertinat
- Centro de Microscopía Avanzada, CMA BIO, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160 C, 4030000 Concepción, Chile.
| |
Collapse
|
19
|
Haythorne E, Rohm M, van de Bunt M, Brereton MF, Tarasov AI, Blacker TS, Sachse G, Silva Dos Santos M, Terron Exposito R, Davis S, Baba O, Fischer R, Duchen MR, Rorsman P, MacRae JI, Ashcroft FM. Diabetes causes marked inhibition of mitochondrial metabolism in pancreatic β-cells. Nat Commun 2019; 10:2474. [PMID: 31171772 PMCID: PMC6554411 DOI: 10.1038/s41467-019-10189-x] [Citation(s) in RCA: 200] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 04/12/2019] [Indexed: 12/21/2022] Open
Abstract
Diabetes is a global health problem caused primarily by the inability of pancreatic β-cells to secrete adequate levels of insulin. The molecular mechanisms underlying the progressive failure of β-cells to respond to glucose in type-2 diabetes remain unresolved. Using a combination of transcriptomics and proteomics, we find significant dysregulation of major metabolic pathways in islets of diabetic βV59M mice, a non-obese, eulipidaemic diabetes model. Multiple genes/proteins involved in glycolysis/gluconeogenesis are upregulated, whereas those involved in oxidative phosphorylation are downregulated. In isolated islets, glucose-induced increases in NADH and ATP are impaired and both oxidative and glycolytic glucose metabolism are reduced. INS-1 β-cells cultured chronically at high glucose show similar changes in protein expression and reduced glucose-stimulated oxygen consumption: targeted metabolomics reveals impaired metabolism. These data indicate hyperglycaemia induces metabolic changes in β-cells that markedly reduce mitochondrial metabolism and ATP synthesis. We propose this underlies the progressive failure of β-cells in diabetes.
Collapse
Affiliation(s)
- Elizabeth Haythorne
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Oxford, OX1 3PT, UK
| | - Maria Rohm
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Oxford, OX1 3PT, UK
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich, Neuherberg, 85764, Germany
| | - Martijn van de Bunt
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7EL, UK
- Department of Bioinformatics and Data Mining, Novo Nordisk A/S, Måløv, 2760, Denmark
| | - Melissa F Brereton
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Oxford, OX1 3PT, UK
| | - Andrei I Tarasov
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7EL, UK
| | - Thomas S Blacker
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Gregor Sachse
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Oxford, OX1 3PT, UK
| | | | - Raul Terron Exposito
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Oxford, OX1 3PT, UK
| | - Simon Davis
- Discovery Proteomics Facility, Target Discovery Institute, University of Oxford, Oxford, OX3 7FZ, UK
| | - Otto Baba
- Tokushima University Graduate School, 3-18-15, Kuramoto-cho, Tokushima, 770-8504, Japan
| | - Roman Fischer
- Discovery Proteomics Facility, Target Discovery Institute, University of Oxford, Oxford, OX3 7FZ, UK
| | - Michael R Duchen
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7EL, UK
- Metabolic Research, Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Göteborg, Box 433, 40530, Göteborg, Sweden
| | - James I MacRae
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Frances M Ashcroft
- Department of Physiology, Anatomy and Genetics and OXION, University of Oxford, Oxford, OX1 3PT, UK.
- Metabolic Research, Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Göteborg, Box 433, 40530, Göteborg, Sweden.
| |
Collapse
|
20
|
Abstract
In the past 3 years, we have seen a flurry of publications on single-cell RNA sequencing (RNA-seq) analyses of pancreatic islets from mouse and human. This technology holds the promise to refine cell-type signatures and discover cellular heterogeneity among the canonical endocrine cell types such as the glucagon-producing α and insulin-producing β cells, going as far as suggesting new subtypes. In addition, single-cell RNA-seq has the ability to characterize rare endocrine cell types that are not captured by prior bulk analysis. With transcriptomics data from individual endocrine cells, cellular states can be profiled both along developmental processes and during the emergence of metabolic diseases. However, the promises of this new technology have not yet been met in full. While the methodology for the first time enabled the transcriptional definition of rare endocrine cell types such as ghrelin-producing ɛ cells, some of the conclusions regarding cell-type-specific gene expression changes in type 2 diabetes might need to be revisited once larger sample sizes become available. Data generation and analysis are continuously improving single-cell RNA-seq approaches and are helping us to understand the (mal)adaptations of the islet cells during development, metabolic challenge, and disease.
Collapse
Affiliation(s)
- Yue J Wang
- Department of Genetics and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, 12-126 Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104-6145, USA
| | - Klaus H Kaestner
- Department of Genetics and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, 12-126 Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104-6145, USA.
| |
Collapse
|
21
|
Inhibition of Lincpint expression affects insulin secretion and apoptosis in mouse pancreatic β cells. Int J Biochem Cell Biol 2018; 104:171-179. [DOI: 10.1016/j.biocel.2018.09.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 09/02/2018] [Accepted: 09/06/2018] [Indexed: 12/27/2022]
|
22
|
Sharma A, Halu A, Decano JL, Padi M, Liu YY, Prasad RB, Fadista J, Santolini M, Menche J, Weiss ST, Vidal M, Silverman EK, Aikawa M, Barabási AL, Groop L, Loscalzo J. Controllability in an islet specific regulatory network identifies the transcriptional factor NFATC4, which regulates Type 2 Diabetes associated genes. NPJ Syst Biol Appl 2018; 4:25. [PMID: 29977601 PMCID: PMC6028434 DOI: 10.1038/s41540-018-0057-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 04/09/2018] [Accepted: 05/04/2018] [Indexed: 01/14/2023] Open
Abstract
Probing the dynamic control features of biological networks represents a new frontier in capturing the dysregulated pathways in complex diseases. Here, using patient samples obtained from a pancreatic islet transplantation program, we constructed a tissue-specific gene regulatory network and used the control centrality (Cc) concept to identify the high control centrality (HiCc) pathways, which might serve as key pathobiological pathways for Type 2 Diabetes (T2D). We found that HiCc pathway genes were significantly enriched with modest GWAS p-values in the DIAbetes Genetics Replication And Meta-analysis (DIAGRAM) study. We identified variants regulating gene expression (expression quantitative loci, eQTL) of HiCc pathway genes in islet samples. These eQTL genes showed higher levels of differential expression compared to non-eQTL genes in low, medium, and high glucose concentrations in rat islets. Among genes with highly significant eQTL evidence, NFATC4 belonged to four HiCc pathways. We asked if the expressions of T2D-associated candidate genes from GWAS and literature are regulated by Nfatc4 in rat islets. Extensive in vitro silencing of Nfatc4 in rat islet cells displayed reduced expression of 16, and increased expression of four putative downstream T2D genes. Overall, our approach uncovers the mechanistic connection of NFATC4 with downstream targets including a previously unknown one, TCF7L2, and establishes the HiCc pathways' relationship to T2D.
Collapse
Affiliation(s)
- Amitabh Sharma
- 1Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115 USA.,2Center for Complex Network Research and Department of Physics, Northeastern University, Boston, MA 02115 USA.,3Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, MA 02215 USA.,4Center for Interdisciplinary Cardiovascular Sciences, Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215 USA
| | - Arda Halu
- 1Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115 USA.,4Center for Interdisciplinary Cardiovascular Sciences, Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215 USA
| | - Julius L Decano
- 4Center for Interdisciplinary Cardiovascular Sciences, Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215 USA
| | - Megha Padi
- 5Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721 USA
| | - Yang-Yu Liu
- 1Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115 USA
| | - Rashmi B Prasad
- 6Lund University Diabetes Center, Department of Clinical Sciences, Diabetes & Endocrinology, Skåne University Hospital Malmö, Lund University, Malmö, 20502 Sweden
| | - Joao Fadista
- 6Lund University Diabetes Center, Department of Clinical Sciences, Diabetes & Endocrinology, Skåne University Hospital Malmö, Lund University, Malmö, 20502 Sweden
| | - Marc Santolini
- 1Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115 USA.,2Center for Complex Network Research and Department of Physics, Northeastern University, Boston, MA 02115 USA
| | - Jörg Menche
- 2Center for Complex Network Research and Department of Physics, Northeastern University, Boston, MA 02115 USA.,7 CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, 1090 Austria
| | - Scott T Weiss
- 1Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115 USA
| | - Marc Vidal
- 3Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, MA 02215 USA.,8Department of Genetics, Harvard Medical School, Boston, MA 02115 USA
| | - Edwin K Silverman
- 1Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115 USA
| | - Masanori Aikawa
- 4Center for Interdisciplinary Cardiovascular Sciences, Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215 USA
| | - Albert-László Barabási
- 1Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115 USA.,2Center for Complex Network Research and Department of Physics, Northeastern University, Boston, MA 02115 USA.,3Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, MA 02215 USA.,9Center for Network Science, Central European University, Nador u. 9, 1051 Budapest, Hungary
| | - Leif Groop
- 6Lund University Diabetes Center, Department of Clinical Sciences, Diabetes & Endocrinology, Skåne University Hospital Malmö, Lund University, Malmö, 20502 Sweden.,10Department of Clinical Sciences, Islet cell physiology, Skåne University Hospital Malmö, Lund University, Malmö, 20502 Sweden
| | - Joseph Loscalzo
- 11Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115 USA
| |
Collapse
|
23
|
Bensellam M, Jonas JC, Laybutt DR. Mechanisms of β-cell dedifferentiation in diabetes: recent findings and future research directions. J Endocrinol 2018; 236:R109-R143. [PMID: 29203573 DOI: 10.1530/joe-17-0516] [Citation(s) in RCA: 158] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 12/04/2017] [Indexed: 12/13/2022]
Abstract
Like all the cells of an organism, pancreatic β-cells originate from embryonic stem cells through a complex cellular process termed differentiation. Differentiation involves the coordinated and tightly controlled activation/repression of specific effectors and gene clusters in a time-dependent fashion thereby giving rise to particular morphological and functional cellular features. Interestingly, cellular differentiation is not a unidirectional process. Indeed, growing evidence suggests that under certain conditions, mature β-cells can lose, to various degrees, their differentiated phenotype and cellular identity and regress to a less differentiated or a precursor-like state. This concept is termed dedifferentiation and has been proposed, besides cell death, as a contributing factor to the loss of functional β-cell mass in diabetes. β-cell dedifferentiation involves: (1) the downregulation of β-cell-enriched genes, including key transcription factors, insulin, glucose metabolism genes, protein processing and secretory pathway genes; (2) the concomitant upregulation of genes suppressed or expressed at very low levels in normal β-cells, the β-cell forbidden genes; and (3) the likely upregulation of progenitor cell genes. These alterations lead to phenotypic reconfiguration of β-cells and ultimately defective insulin secretion. While the major role of glucotoxicity in β-cell dedifferentiation is well established, the precise mechanisms involved are still under investigation. This review highlights the identified molecular mechanisms implicated in β-cell dedifferentiation including oxidative stress, endoplasmic reticulum (ER) stress, inflammation and hypoxia. It discusses the role of Foxo1, Myc and inhibitor of differentiation proteins and underscores the emerging role of non-coding RNAs. Finally, it proposes a novel hypothesis of β-cell dedifferentiation as a potential adaptive mechanism to escape cell death under stress conditions.
Collapse
Affiliation(s)
- Mohammed Bensellam
- Garvan Institute of Medical ResearchSydney, New South Wales, Australia
- Université Catholique de LouvainInstitut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Jean-Christophe Jonas
- Université Catholique de LouvainInstitut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - D Ross Laybutt
- Garvan Institute of Medical ResearchSydney, New South Wales, Australia
- St Vincent's Clinical SchoolUNSW Sydney, Sydney, New South Wales, Australia
| |
Collapse
|
24
|
Rodríguez-Comas J, Moreno-Asso A, Moreno-Vedia J, Martín M, Castaño C, Marzà-Florensa A, Bofill-De Ros X, Mir-Coll J, Montané J, Fillat C, Gasa R, Novials A, Servitja JM. Stress-Induced MicroRNA-708 Impairs β-Cell Function and Growth. Diabetes 2017; 66:3029-3040. [PMID: 28970284 DOI: 10.2337/db16-1569] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 09/24/2017] [Indexed: 11/13/2022]
Abstract
The pancreatic β-cell transcriptome is highly sensitive to external signals such as glucose oscillations and stress cues. MicroRNAs (miRNAs) have emerged as key factors in gene expression regulation. Here, we aimed to identify miRNAs that are modulated by glucose in mouse pancreatic islets. We identified miR-708 as the most upregulated miRNA in islets cultured at low glucose concentrations, a setting that triggers a strong stress response. miR-708 was also potently upregulated by triggering endoplasmic reticulum (ER) stress with thapsigargin and in islets of ob/ob mice. Low-glucose induction of miR-708 was blocked by treatment with the chemical chaperone 4-phenylbutyrate, uncovering the involvement of ER stress in this response. An integrative analysis identified neuronatin (Nnat) as a potential glucose-regulated target of miR-708. Indeed, Nnat expression was inversely correlated with miR-708 in islets cultured at different glucose concentrations and in ob/ob mouse islets and was reduced after miR-708 overexpression. Consistent with the role of Nnat in the secretory function of β-cells, miR-708 overexpression impaired glucose-stimulated insulin secretion (GSIS), which was recovered by NNAT overexpression. Moreover, miR-708 inhibition recovered GSIS in islets cultured at low glucose. Finally, miR-708 overexpression suppressed β-cell proliferation and induced β-cell apoptosis. Collectively, our results provide a novel mechanism of glucose regulation of β-cell function and growth by repressing stress-induced miR-708.
Collapse
Affiliation(s)
- Júlia Rodríguez-Comas
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Alba Moreno-Asso
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas (CIBERDEM), Barcelona, Spain
| | - Juan Moreno-Vedia
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Mercè Martín
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Carlos Castaño
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas (CIBERDEM), Barcelona, Spain
| | - Anna Marzà-Florensa
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Xavier Bofill-De Ros
- Gene Therapy and Cancer Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Barcelona, Spain
| | - Joan Mir-Coll
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Department of Medicine, University of Barcelona, Barcelona, Spain
| | - Joel Montané
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas (CIBERDEM), Barcelona, Spain
| | - Cristina Fillat
- Gene Therapy and Cancer Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Barcelona, Spain
| | - Rosa Gasa
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas (CIBERDEM), Barcelona, Spain
| | - Anna Novials
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas (CIBERDEM), Barcelona, Spain
| | - Joan-Marc Servitja
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas (CIBERDEM), Barcelona, Spain
| |
Collapse
|
25
|
Giacconi R, Cai L, Costarelli L, Cardelli M, Malavolta M, Piacenza F, Provinciali M. Implications of impaired zinc homeostasis in diabetic cardiomyopathy and nephropathy. Biofactors 2017; 43:770-784. [PMID: 28845600 DOI: 10.1002/biof.1386] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 07/12/2017] [Accepted: 07/27/2017] [Indexed: 12/18/2022]
Abstract
Impaired zinc homeostasis is observed in diabetes mellitus (DM2) and its complications. Zinc has a specific role in pancreatic β-cells via insulin synthesis, storage, and secretion. Intracellular zinc homeostasis is tightly controlled by zinc transporters (ZnT and Zip families) and metallothioneins (MT) which modulate the uptake, storage, and distribution of zinc. Several investigations in animal models demonstrate the protective role of MT in DM2 and its cardiovascular or renal complications, while a copious literature shows that a common polymorphism (R325W) in ZnT8, which affects the protein's zinc transport activity, is associated with increased DM2 risk. Emerging studies highlight a role of other zinc transporters in β-cell function, suggesting that targeting them could make a possible contribution in managing the hyperglycemia in diabetic patients. This article summarizes the current findings concerning the role of zinc homeostasis in DM2 pathogenesis and development of diabetic cardiomyopathy and nephropathy and suggests novel therapeutic targets. © 2017 BioFactors, 43(6):770-784, 2017.
Collapse
Affiliation(s)
- Robertina Giacconi
- Translational Research Center of Nutrition and Ageing, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Lu Cai
- Pediatric Research Institute at the Department of Pediatrics, Wendy L. Novak Diabetes Care Center, University of Louisville, Louisville, KY, USA
| | - Laura Costarelli
- Translational Research Center of Nutrition and Ageing, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Maurizio Cardelli
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Marco Malavolta
- Translational Research Center of Nutrition and Ageing, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Francesco Piacenza
- Translational Research Center of Nutrition and Ageing, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| | - Mauro Provinciali
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, Italian National Institute of Health and Science on Aging (INRCA), Ancona, Italy
| |
Collapse
|
26
|
Lawson R, Maret W, Hogstrand C. Expression of the ZIP/SLC39A transporters in β-cells: a systematic review and integration of multiple datasets. BMC Genomics 2017; 18:719. [PMID: 28893192 PMCID: PMC5594519 DOI: 10.1186/s12864-017-4119-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 09/05/2017] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Pancreatic β-cells require a constant supply of zinc to maintain normal insulin secretory function. Following co-exocytosis with insulin, zinc is replenished via the Zrt- and Irt-like (ZIP; SLC39A) family of transporters. However the ZIP paralogues of particular importance for zinc uptake, and associations with β-cell function and Type 2 Diabetes remain largely unexplored. We retrieved and statistically analysed publically available microarray and RNA-seq datasets to perform a systematic review on the expression of β-cell SLC39A paralogues. We complemented results with experimental data on expression profiling of human islets and mouse β-cell derived MIN6 cells, and compared transcriptomic and proteomic sequence conservation between human, mouse and rat. RESULTS The 14 ZIP paralogues have 73-98% amino sequence conservation between human and rodents. We identified 18 datasets for β-cell SLC39A analysis, which compared relative expression to non-β-cells, and expression in response to PDX-1 activity, cytokines, glucose and type 2 diabetic status. Published expression data demonstrate enrichment of transcripts for ZIP7 and ZIP9 transporters within rodent β-cells and of ZIP6, ZIP7 and ZIP14 within human β-cells, with ZIP1 most differentially expressed in response to cytokines and PDX-1 within rodent, and ZIP6 in response to diabetic status in human and glucose in rat. Our qPCR expression profiling data indicate that SLC39A6, -9, -13, and - 14 are the highest expressed paralogues in human β-cells and Slc39a6 and -7 in MIN6 cells. CONCLUSIONS Our systematic review, expression profiling and sequence alignment reveal similarities and potentially important differences in ZIP complements between human and rodent β-cells. We identify ZIP6, ZIP7, ZIP9, ZIP13 and ZIP14 in human and rodent and ZIP1 in rodent as potentially biologically important for β-cell zinc trafficking. We propose ZIP6 and ZIP7 are key functional orthologues in human and rodent β-cells and highlight these zinc importers as important targets for exploring associations between zinc status and normal physiology of β-cells and their decline in Type 2 Diabetes.
Collapse
Affiliation(s)
- Rebecca Lawson
- King's College London, Faculty of Life Sciences and Medicine, Diabetes and Nutritional Sciences, Metal Metabolism Group, 150 Stamford St, London, SE1 9NH, UK
| | - Wolfgang Maret
- King's College London, Faculty of Life Sciences and Medicine, Diabetes and Nutritional Sciences, Metal Metabolism Group, 150 Stamford St, London, SE1 9NH, UK
| | - Christer Hogstrand
- King's College London, Faculty of Life Sciences and Medicine, Diabetes and Nutritional Sciences, Metal Metabolism Group, 150 Stamford St, London, SE1 9NH, UK.
| |
Collapse
|
27
|
Mihailidou C, Chatzistamou I, Papavassiliou AG, Kiaris H. Modulation of Pancreatic Islets' Function and Survival During Aging Involves the Differential Regulation of Endoplasmic Reticulum Stress by p21 and CHOP. Antioxid Redox Signal 2017; 27:185-200. [PMID: 27931122 PMCID: PMC5512329 DOI: 10.1089/ars.2016.6671] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
AIMS Although endoplasmic reticulum (ER) stress is recognized as a major mechanism causing pancreatic dysfunction in diabetes, little is known on how aging modulates the process. Here, we compared the response with ER stress, viability, and insulin release from pancreatic islets of young (6 weeks) or aged (14 months) mice. RESULTS Islets from aged mice were more sensitive to ER stress than their younger counterparts; they exhibited more pronounced unfolded protein response (UPR) and caspase activation and displayed compromised insulin release after high-glucose stimulation. Genetic ablation of p21 sensitized the islets to ER stress, especially in the aged group, whereas CHOP ablation was protective for islets from both aged and younger animals. Ciclopirox (CPX), an iron chelator that stimulates p21 expression, protected islets from glucotoxicity and mice from diet-induced diabetes, especially in the aged group in a manner that was both p21 and CHOP dependent. INNOVATION For the first time, the study shows that age-dependent susceptibility to diet-induced diabetes is associated with the activity of p21 and CHOP in pancreatic islets and that CPX protects islets from glucotoxicity and mice from diabetes in an age-dependent manner. CONCLUSIONS Our results identify ER stress as an age-dependent modifier of islet survival and function by mechanisms implicating enhancement of CHOP activity and inhibition of the protective activity of p21. These findings suggest that interventions restoring the homeostatic activity of ER stress, by agents such as CPX, may be particularly beneficial for the management of diabetes in the elderly. Antioxid. Redox Signal. 27, 185-200.
Collapse
Affiliation(s)
- Chrysovalantou Mihailidou
- 1 Department of Biological Chemistry, National and Kapodistrian University of Athens , Medical School, Athens, Greece
| | - Ioulia Chatzistamou
- 2 Department of Pathology, Microbiology and Immunology, University of South Carolina School of Medicine , Columbia, South Carolina
| | - Athanasios G Papavassiliou
- 1 Department of Biological Chemistry, National and Kapodistrian University of Athens , Medical School, Athens, Greece
| | - Hippokratis Kiaris
- 1 Department of Biological Chemistry, National and Kapodistrian University of Athens , Medical School, Athens, Greece .,3 Department of Drug Discovery and Biomedical Sciences, University of South Carolina , Columbia, South Carolina
| |
Collapse
|
28
|
Ashcroft FM, Rohm M, Clark A, Brereton MF. Is Type 2 Diabetes a Glycogen Storage Disease of Pancreatic β Cells? Cell Metab 2017; 26:17-23. [PMID: 28683284 PMCID: PMC5890904 DOI: 10.1016/j.cmet.2017.05.014] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 04/24/2017] [Accepted: 05/24/2017] [Indexed: 11/17/2022]
Abstract
Elevated plasma glucose leads to pancreatic β cell dysfunction and death in type 2 diabetes. Glycogen accumulation, due to impaired metabolism, contributes to this "glucotoxicity" via dysregulated biochemical pathways promoting β cell dysfunction. Here, we review emerging data, and re-examine published findings, on the role of glycogen in β cells in normoglycemia and in diabetes.
Collapse
Affiliation(s)
- Frances M Ashcroft
- Department of Physiology, Anatomy, and Genetics and OXION, University of Oxford, Parks Road, Oxford OX1 3PT, UK.
| | - Maria Rohm
- Department of Physiology, Anatomy, and Genetics and OXION, University of Oxford, Parks Road, Oxford OX1 3PT, UK
| | - Anne Clark
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Melissa F Brereton
- Department of Physiology, Anatomy, and Genetics and OXION, University of Oxford, Parks Road, Oxford OX1 3PT, UK
| |
Collapse
|
29
|
Dalgaard LT, Eliasson L. An 'alpha-beta' of pancreatic islet microribonucleotides. Int J Biochem Cell Biol 2017; 88:208-219. [PMID: 28122254 DOI: 10.1016/j.biocel.2017.01.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 01/16/2017] [Accepted: 01/18/2017] [Indexed: 11/17/2022]
Abstract
MicroRNAs (miRNAs) are cellular, short, non-coding ribonucleotides acting as endogenous posttranscriptional repressors following incorporation in the RNA-induced silencing complex. Despite being chemically and mechanistically very similar, miRNAs exert a multitude of different cellular effects by acting on mRNA species, whose gene-products partake in a wide array of processes. Here, the aim was to review the knowledge of miRNA expression and action in the islet of Langerhans. We have focused on: 1) physiological consequences of islet or beta cell specific inhibition of miRNA processing, 2) mechanisms regulating processing of miRNAs in islet cells, 3) presence and function of miRNAs in alpha versus beta cells - the two main cell types of islets, and 4) miRNA mediators of beta cell decompensation. It is clear that miRNAs regulate pancreatic islet development, maturation, and function in vivo. Moreover, processing of miRNAs appears to be altered by obesity, diabetes, and aging. A number of miRNAs (such as miR-7, miR-21, miR-29, miR-34a, miR-212/miR-132, miR-184, miR-200 and miR-375) are involved in mediating beta cell dysfunction and/or compensation induced by hyperglycemia, oxidative stress, cytotoxic cytokines, and in rodent models of fetal metabolic programming prediabetes and overt diabetes. Studies of human type 2 diabetic islets underline that these miRNA families could have important roles also in human type 2 diabetes. Furthermore, there is a genuine gap of knowledge regarding miRNA expression and function in pancreatic alpha cells. Progress in this area would be enhanced by improved in vitro alpha cell models and better tools for islet cell sorting.
Collapse
Affiliation(s)
| | - Lena Eliasson
- Lund University Diabetes Center, Department of Clinical Sciences Malmö, CRC, SUS, Malmö, Sweden.
| |
Collapse
|
30
|
Determining Cutoff Point of Ensemble Trees Based on Sample Size in Predicting Clinical Dose with DNA Microarray Data. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2017; 2016:6794916. [PMID: 28096893 PMCID: PMC5206477 DOI: 10.1155/2016/6794916] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 11/18/2016] [Accepted: 11/27/2016] [Indexed: 11/21/2022]
Abstract
Background/Aim. Evaluating the success of dose prediction based on genetic or clinical data has substantially advanced recently. The aim of this study is to predict various clinical dose values from DNA gene expression datasets using data mining techniques. Materials and Methods. Eleven real gene expression datasets containing dose values were included. First, important genes for dose prediction were selected using iterative sure independence screening. Then, the performances of regression trees (RTs), support vector regression (SVR), RT bagging, SVR bagging, and RT boosting were examined. Results. The results demonstrated that a regression-based feature selection method substantially reduced the number of irrelevant genes from raw datasets. Overall, the best prediction performance in nine of 11 datasets was achieved using SVR; the second most accurate performance was provided using a gradient-boosting machine (GBM). Conclusion. Analysis of various dose values based on microarray gene expression data identified common genes found in our study and the referenced studies. According to our findings, SVR and GBM can be good predictors of dose-gene datasets. Another result of the study was to identify the sample size of n = 25 as a cutoff point for RT bagging to outperform a single RT.
Collapse
|
31
|
de Souza AH, Santos LRB, Roma LP, Bensellam M, Carpinelli AR, Jonas JC. NADPH oxidase-2 does not contribute to β-cell glucotoxicity in cultured pancreatic islets from C57BL/6J mice. Mol Cell Endocrinol 2017; 439:354-362. [PMID: 27664519 DOI: 10.1016/j.mce.2016.09.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 08/24/2016] [Accepted: 09/20/2016] [Indexed: 11/20/2022]
Abstract
High glucose-induced oxidative stress and increased NADPH oxidase-2 (NOX2) activity may contribute to the progressive decline of the functional β-cell mass in type 2 diabetes. To test that hypothesis, we characterized, in islets from male NOX2 knockout (NOX2-KO) and wild-type (WT) C57BL/6J mice cultured for up to 3 weeks at 10 or 30 mmol/l glucose (G10 or G30), the in vitro effects of glucose on cytosolic oxidative stress using probes sensing glutathione oxidation (GRX1-roGFP2), thiol oxidation (roGFP1) or H2O2 (roGFP2-Orp1), on β-cell stimulus-secretion coupling events and on β-cell apoptosis. After 1-2 days of culture in G10, the glucose stimulation of insulin secretion (GSIS) was ∼1.7-fold higher in NOX2-KO vs. WT islets at 20-30 mmol/l glucose despite similar rises in NAD(P)H and intracellular calcium concentration ([Ca2+]i) and no differences in cytosolic GRX1-roGFP2 oxidation. After long-term culture at G10, roGFP1 and roGFP2-Orp1 oxidation and β-cell apoptosis remained low, and the glucose-induced rises in NAD(P)H, [Ca2+]i and GSIS were similarly preserved in both islet types. After prolonged culture at G30, roGFP1 and roGFP2-Orp1 oxidation increased in parallel with β-cell apoptosis, the glucose sensitivity of the NADPH, [Ca2+]i and insulin secretion responses increased, the maximal [Ca2+]i response decreased, but maximal GSIS was preserved. These responses were almost identical in both islet types. In conclusion, NOX2 is a negative regulator of maximal GSIS in C57BL/6J mouse islets, but it does not detectably contribute to the in vitro glucotoxic induction of cytosolic oxidative stress and alterations of β-cell survival and function.
Collapse
Affiliation(s)
- Arnaldo H de Souza
- Université catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Brussels, Belgium; Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Laila R B Santos
- Université catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Brussels, Belgium
| | - Leticia P Roma
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Mohammed Bensellam
- Université catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Brussels, Belgium
| | - Angelo R Carpinelli
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Jean-Christophe Jonas
- Université catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Brussels, Belgium.
| |
Collapse
|
32
|
Singh R, Kursan S, Almiahoub MY, Almutairi MM, Garzón-Muvdi T, Alvarez-Leefmans FJ, Di Fulvio M. Plasma Membrane Targeting of Endogenous NKCC2 in COS7 Cells Bypasses Functional Golgi Cisternae and Complex N-Glycosylation. Front Cell Dev Biol 2017; 4:150. [PMID: 28101499 PMCID: PMC5209364 DOI: 10.3389/fcell.2016.00150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 12/14/2016] [Indexed: 12/04/2022] Open
Abstract
Na+K+2Cl− co-transporters (NKCCs) effect the electroneutral movement of Na+-K+ and 2Cl− ions across the plasma membrane of vertebrate cells. There are two known NKCC isoforms, NKCC1 (Slc12a2) and NKCC2 (Slc12a1). NKCC1 is a ubiquitously expressed transporter involved in cell volume regulation, Cl− homeostasis and epithelial salt secretion, whereas NKCC2 is abundantly expressed in kidney epithelial cells of the thick ascending loop of Henle, where it plays key roles in NaCl reabsorption and electrolyte homeostasis. Although NKCC1 and NKCC2 co-transport the same ions with identical stoichiometry, NKCC1 actively co-transports water whereas NKCC2 does not. There is growing evidence showing that NKCC2 is expressed outside the kidney, but its function in extra-renal tissues remains unknown. The present study shows molecular and functional evidence of endogenous NKCC2 expression in COS7 cells, a widely used mammalian cell model. Endogenous NKCC2 is primarily found in recycling endosomes, Golgi cisternae, Golgi-derived vesicles, and to a lesser extent in the endoplasmic reticulum. Unlike NKCC1, NKCC2 is minimally hybrid/complex N-glycosylated under basal conditions and yet it is trafficked to the plasma membrane region of hyper-osmotically challenged cells through mechanisms that require minimal complex N-glycosylation or functional Golgi cisternae. Control COS7 cells exposed to slightly hyperosmotic (~6.7%) solutions for 16 h were not shrunken, suggesting that either one or both NKCC1 and NKCC2 may participate in cell volume recovery. However, NKCC2 targeted to the plasma membrane region or transient over-expression of NKCC2 failed to rescue NKCC1 in COS7 cells where NKCC1 had been silenced. Further, COS7 cells in which NKCC1, but not NKCC2, was silenced exhibited reduced cell size compared to control cells. Altogether, these results suggest that NKCC2 does not participate in cell volume recovery and therefore, NKCC1 and NKCC2 are functionally different Na+K+2Cl− co-transporters.
Collapse
Affiliation(s)
- Richa Singh
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Shams Kursan
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Mohamed Y Almiahoub
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Mohammed M Almutairi
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Tomás Garzón-Muvdi
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Francisco J Alvarez-Leefmans
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Mauricio Di Fulvio
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| |
Collapse
|
33
|
Sharp J, Vermette P. An In-situ
glucose-stimulated insulin secretion assay under perfusion bioreactor conditions. Biotechnol Prog 2016; 33:454-462. [DOI: 10.1002/btpr.2407] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 09/23/2016] [Indexed: 12/28/2022]
Affiliation(s)
- Jamie Sharp
- Laboratoire de bio-ingénierie et de biophysique de l'Université de Sherbrooke, Dept. of Chemical and Biotechnological Engineering; Université de Sherbrooke; 2500 boulevard de l'Université Sherbrooke QC J1K 2R1 Canada
| | - Patrick Vermette
- Laboratoire de bio-ingénierie et de biophysique de l'Université de Sherbrooke, Dept. of Chemical and Biotechnological Engineering; Université de Sherbrooke; 2500 boulevard de l'Université Sherbrooke QC J1K 2R1 Canada
| |
Collapse
|
34
|
Hals IK, Singh R, Ma Z, Scholz H, Björklund A, Grill V. Culture at low glucose up-regulates mitochondrial function in pancreatic β cells with accompanying effects on viability. Islets 2016; 8:165-176. [PMID: 27763807 PMCID: PMC5161144 DOI: 10.1080/19382014.2016.1246637] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
We tested whether exposure of β cells at reduced glucose leads to mitochondrial adaptions and whether such adaptions modulate effects of hypoxia. Rat islets, human islets and INS-1 832/13 cells were pre-cultured short term at half standard glucose concentrations (5.5 mM for rat islets and cells, 2.75 mM for human islets) without overtly negative effects on subsequently measured function (insulin secretion and cellular insulin contents) or on viability. Culture at half standard glucose upregulated complex I and tended to upregulate complex II in islets and INS-1 cells alike. An increased release of lactate dehydrogenase that followed exposure to hypoxia was attenuated in rat islets which had been pre-cultured at half standard glucose. In INS-1 cells exposure to half standard glucose attenuated hypoxia-induced effects on several viability parameters (MTT, cell number and incremental apoptotic DNA). Thus culture at reduced glucose of pancreatic islets and clonal β cells leads to mitochondrial adaptions which possibly lessen the negative impact of hypoxia on β cell viability. These findings appear relevant in the search for optimization of pre-transplant conditions in a clinical setting.
Collapse
Affiliation(s)
- Ingrid K. Hals
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
- Department of Endocrinology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway
- CONTACT Ingrid K. Hals Department of Cancer Research and Molecular Medicine, NTNU, Gastrosenter, St Olavs Hospital, Prinsesse Kristinas gate 1, 7006 Trondheim, Norway
| | - Rinku Singh
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Zuheng Ma
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Hanne Scholz
- Department of Transplantation Medicine and Institute for Surgical Research, Oslo University Hospital, Oslo, Norway
| | - Anneli Björklund
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Valdemar Grill
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
- Department of Endocrinology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway
| |
Collapse
|
35
|
Schmidt SF, Madsen JGS, Frafjord KØ, Poulsen LLC, Salö S, Boergesen M, Loft A, Larsen BD, Madsen MS, Holst JJ, Maechler P, Dalgaard LT, Mandrup S. Integrative Genomics Outlines a Biphasic Glucose Response and a ChREBP-RORγ Axis Regulating Proliferation in β Cells. Cell Rep 2016; 16:2359-72. [PMID: 27545881 DOI: 10.1016/j.celrep.2016.07.063] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/26/2016] [Accepted: 07/25/2016] [Indexed: 12/27/2022] Open
Abstract
Glucose is an important inducer of insulin secretion, but it also stimulates long-term adaptive changes in gene expression that can either promote or antagonize the proliferative potential and function of β cells. Here, we have generated time-resolved profiles of enhancer and transcriptional activity in response to glucose in the INS-1E pancreatic β cell line. Our data outline a biphasic response with a first transcriptional wave during which metabolic genes are activated, and a second wave where cell-cycle genes are activated and β cell identity genes are repressed. The glucose-sensing transcription factor ChREBP directly activates first wave enhancers, whereas repression and activation of second wave enhancers are indirect. By integrating motif enrichment within late-regulated enhancers with expression profiles of the associated transcription factors, we have identified multiple putative regulators of the second wave. These include RORγ, the activity of which is important for glucose-induced proliferation of both INS-1E and primary rat β cells.
Collapse
Affiliation(s)
- Søren Fisker Schmidt
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
| | - Jesper Grud Skat Madsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark; NNF Center of Basic Metabolic Research, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Kari Østerli Frafjord
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
| | - Lars la Cour Poulsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
| | - Sofia Salö
- Department of Science and Environment, Roskilde University, 4000 Roskilde, Denmark
| | - Michael Boergesen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
| | - Anne Loft
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
| | - Bjørk Ditlev Larsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
| | - Maria Stahl Madsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
| | - Jens Juul Holst
- NNF Center of Basic Metabolic Research, University of Copenhagen, 2200 Copenhagen N, Denmark; Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Pierre Maechler
- Department of Cell Physiology and Metabolism, University of Geneva, 1211 Geneva, Switzerland
| | - Louise Torp Dalgaard
- Department of Science and Environment, Roskilde University, 4000 Roskilde, Denmark
| | - Susanne Mandrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark.
| |
Collapse
|
36
|
Lemaire K, Thorrez L, Schuit F. Disallowed and Allowed Gene Expression: Two Faces of Mature Islet Beta Cells. Annu Rev Nutr 2016; 36:45-71. [DOI: 10.1146/annurev-nutr-071715-050808] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Lieven Thorrez
- Gene Expression Unit, Department of Cellular and Molecular Medicine, Faculty of Medicine, KU Leuven, Leuven B3000, Belgium; , ,
| | - Frans Schuit
- Gene Expression Unit, Department of Cellular and Molecular Medicine, Faculty of Medicine, KU Leuven, Leuven B3000, Belgium; , ,
| |
Collapse
|
37
|
Bensellam M, Maxwell EL, Chan JY, Luzuriaga J, West PK, Jonas JC, Gunton JE, Laybutt DR. Hypoxia reduces ER-to-Golgi protein trafficking and increases cell death by inhibiting the adaptive unfolded protein response in mouse beta cells. Diabetologia 2016; 59:1492-1502. [PMID: 27039902 DOI: 10.1007/s00125-016-3947-y] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 03/16/2016] [Indexed: 12/13/2022]
Abstract
AIMS/HYPOTHESIS Hypoxia may contribute to beta cell failure in type 2 diabetes and islet transplantation. The adaptive unfolded protein response (UPR) is required for endoplasmic reticulum (ER) homeostasis. Here we investigated whether or not hypoxia regulates the UPR in beta cells and the role the adaptive UPR plays during hypoxic stress. METHODS Mouse islets and MIN6 cells were exposed to various oxygen (O2) tensions. DNA-damage inducible transcript 3 (DDIT3), hypoxia-inducible transcription factor (HIF)1α and HSPA5 were knocked down using small interfering (si)RNA; Hspa5 was also overexpressed. db/db mice were used. RESULTS Hypoxia-response genes were upregulated in vivo in the islets of diabetic, but not prediabetic, db/db mice. In isolated mouse islets and MIN6 cells, O2 deprivation (1-5% vs 20%; 4-24 h) markedly reduced the expression of adaptive UPR genes, including Hspa5, Hsp90b1, Fkbp11 and spliced Xbp1. Coatomer protein complex genes (Copa, Cope, Copg [also known as Copg1], Copz1 and Copz2) and ER-to-Golgi protein trafficking were also reduced, whereas apoptotic genes (Ddit3, Atf3 and Trb3 [also known as Trib3]), c-Jun N-terminal kinase (JNK) phosphorylation and cell death were increased. Inhibition of JNK, but not HIF1α, restored adaptive UPR gene expression and ER-to-Golgi protein trafficking while protecting against apoptotic genes and cell death following hypoxia. DDIT3 knockdown delayed the loss of the adaptive UPR and partially protected against hypoxia-induced cell death. The latter response was prevented by HSPA5 knockdown. Finally, Hspa5 overexpression significantly protected against hypoxia-induced cell death. CONCLUSIONS/INTERPRETATION Hypoxia inhibits the adaptive UPR in beta cells via JNK and DDIT3 activation, but independently of HIF1α. Downregulation of the adaptive UPR contributes to reduced ER-to-Golgi protein trafficking and increased beta cell death during hypoxic stress.
Collapse
Affiliation(s)
- Mohammed Bensellam
- Garvan Institute of Medical Research, St Vincent's Hospital, UNSW Australia, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia
| | - Emma L Maxwell
- Garvan Institute of Medical Research, St Vincent's Hospital, UNSW Australia, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia
| | - Jeng Yie Chan
- Garvan Institute of Medical Research, St Vincent's Hospital, UNSW Australia, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia
| | - Jude Luzuriaga
- Garvan Institute of Medical Research, St Vincent's Hospital, UNSW Australia, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia
| | - Phillip K West
- Garvan Institute of Medical Research, St Vincent's Hospital, UNSW Australia, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia
| | - Jean-Christophe Jonas
- Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Brussels, Belgium
| | - Jenny E Gunton
- Garvan Institute of Medical Research, St Vincent's Hospital, UNSW Australia, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia
- Westmead Hospital, Sydney, NSW, Australia
- The Westmead Millennium Institute for Medical Research, The University of Sydney, Sydney, NSW, Australia
| | - D Ross Laybutt
- Garvan Institute of Medical Research, St Vincent's Hospital, UNSW Australia, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia.
| |
Collapse
|
38
|
Brun T, Maechler P. Beta-cell mitochondrial carriers and the diabetogenic stress response. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2540-9. [PMID: 26979549 DOI: 10.1016/j.bbamcr.2016.03.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 01/09/2023]
Abstract
Mitochondria play a central role in pancreatic beta-cells by coupling metabolism of the secretagogue glucose to distal events of regulated insulin exocytosis. This process requires transports of both metabolites and nucleotides in and out of the mitochondria. The molecular identification of mitochondrial carriers and their respective contribution to beta-cell function have been uncovered only recently. In type 2 diabetes, mitochondrial dysfunction is an early event and may precipitate beta-cell loss. Under diabetogenic conditions, characterized by glucotoxicity and lipotoxicity, the expression profile of mitochondrial carriers is selectively modified. This review describes the role of mitochondrial carriers in beta-cells and the selective changes in response to glucolipotoxicity. In particular, we discuss the importance of the transfer of metabolites (pyruvate, citrate, malate, and glutamate) and nucleotides (ATP, NADH, NADPH) for beta-cell function and dysfunction. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.
Collapse
Affiliation(s)
- Thierry Brun
- Department of Cell Physiology and Metabolism, Faculty Diabetes Center, Geneva University Medical Centre, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland
| | - Pierre Maechler
- Department of Cell Physiology and Metabolism, Faculty Diabetes Center, Geneva University Medical Centre, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland.
| |
Collapse
|
39
|
Ye W, Zheng Y, Zhang S, Yan L, Cheng H, Wu M. Oxamate Improves Glycemic Control and Insulin Sensitivity via Inhibition of Tissue Lactate Production in db/db Mice. PLoS One 2016; 11:e0150303. [PMID: 26938239 PMCID: PMC4777529 DOI: 10.1371/journal.pone.0150303] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 02/02/2016] [Indexed: 12/18/2022] Open
Abstract
Oxamate (OXA) is a pyruvate analogue that directly inhibits the lactate dehydrogenase (LDH)-catalyzed conversion process of pyruvate into lactate. Earlier and recent studies have shown elevated blood lactate levels among insulin-resistant and type 2 diabetes subjects and that blood lactate levels independently predicted the development of incident diabetes. To explore the potential of OXA in the treatment of diabetes, db/db mice were treated with OXA in vivo. Treatment of OXA (350–750 mg/kg of body weight) for 12 weeks was shown to decrease body weight gain and blood glucose and HbA1c levels and improve insulin secretion, the morphology of pancreatic islets, and insulin sensitivity in db/db mice. Meanwhile, OXA reduced the lactate production of adipose tissue and skeletal muscle and serum lactate levels and decreased serum levels of TG, FFA, CRP, IL-6, and TNF-α in db/db mice. The PCR array showed that OXA downregulated the expression of Tnf, Il6, leptin, Cxcr3, Map2k1, and Ikbkb, and upregulated the expression of Irs2, Nfkbia, and Pde3b in the skeletal muscle of db/db mice. Interestingly, LDH-A expression increased in the islet cells of db/db mice, and both treatment of OXA and pioglitazone decreased LDH-A expression, which might be related to the improvement of insulin secretion. Taken together, increased lactate production of adipose tissue and skeletal muscle may be at least partially responsible for insulin resistance and diabetes in db/db mice. OXA improved glycemic control and insulin sensitivity in db/db mice primarily via inhibition of tissue lactate production. Oxamic acid derivatives may be a potential drug for the treatment of type 2 diabetes.
Collapse
Affiliation(s)
- Weiran Ye
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, P. R. China
| | - Yijia Zheng
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, P. R. China
| | - Shanshan Zhang
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, P. R. China
| | - Li Yan
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, P. R. China
| | - Hua Cheng
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, P. R. China
| | - Muchao Wu
- Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, P. R. China
- * E-mail:
| |
Collapse
|
40
|
Sweeney E, Crainiceanu C, Gertheiss J. Testing differentially expressed genes in dose-response studies and with ordinal phenotypes. Stat Appl Genet Mol Biol 2016; 15:213-35. [DOI: 10.1515/sagmb-2015-0091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
AbstractWhen testing for differentially expressed genes between more than two groups, the groups are often defined by dose levels in dose-response experiments or ordinal phenotypes, such as disease stages. We discuss the potential of a new approach that uses the levels’ ordering without making any structural assumptions, such as monotonicity, by testing for zero variance components in a mixed models framework. Since the mixed effects model approach borrows strength across doses/levels, the test proposed can also be applied when the number of dose levels/phenotypes is large and/or the number of subjects per group is small. We illustrate the new test in simulation studies and on several publicly available datasets and compare it to alternative testing procedures. All tests considered are implemented in R and are publicly available. The new approach offers a very fast and powerful way to test for differentially expressed genes between ordered groups without making restrictive assumptions with respect to the true relationship between factor levels and response.
Collapse
|
41
|
Alshahrani S, Almutairi MM, Kursan S, Dias-Junior E, Almiahuob MM, Aguilar-Bryan L, Di Fulvio M. Increased Slc12a1 expression in β-cells and improved glucose disposal in Slc12a2 heterozygous mice. J Endocrinol 2015; 227:153-65. [PMID: 26400961 PMCID: PMC4623298 DOI: 10.1530/joe-15-0327] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/23/2015] [Indexed: 12/26/2022]
Abstract
The products of the Slc12a1 and Slc12a2 genes, commonly known as Na(+)-dependent K(+)2Cl(-) co-transporters NKCC2 and NKCC1, respectively, are the targets for the diuretic bumetanide. NKCCs are implicated in the regulation of intracellular chloride concentration ([Cl(-)]i) in pancreatic β-cells, and as such, they may play a role in glucose-stimulated plasma membrane depolarization and insulin secretion. Unexpectedly, permanent elimination of NKCC1 does not preclude insulin secretion, an event potentially linked to the homeostatic regulation of additional Cl(-) transporters expressed in β-cells. In this report we provide evidence for such a mechanism. Mice lacking a single allele of Slc12a2 exhibit lower fasting glycemia, increased acute insulin response (AIR) and lower blood glucose levels 15-30 min after a glucose load when compared to mice harboring both alleles of the gene. Furthermore, heterozygous expression or complete absence of Slc12a2 associates with increased NKCC2 protein expression in rodent pancreatic β-cells. This has been confirmed by using chronic pharmacological down-regulation of NKCC1 with bumetanide in the mouse MIN6 β-cell line or permanent molecular silencing of NKCC1 in COS7 cells, which results in increased NKCC2 expression. Furthermore, MIN6 cells chronically pretreated with bumetanide exhibit increased initial rates of Cl(-) uptake while preserving glucose-stimulated insulin secretion. Together, our results suggest that NKCCs are involved in insulin secretion and that a single Slc12a2 allele may protect β-cells from failure due to increased homeostatic expression of Slc12a1.
Collapse
Affiliation(s)
- Saeed Alshahrani
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
| | - Mohammed Mashari Almutairi
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
| | - Shams Kursan
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
| | - Eduardo Dias-Junior
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
| | - Mohamed Mahmoud Almiahuob
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
| | - Lydia Aguilar-Bryan
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
| | - Mauricio Di Fulvio
- Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA
| |
Collapse
|
42
|
Roma LP, Duprez J, Jonas JC. Glucokinase activation is beneficial or toxic to cultured rat pancreatic islets depending on the prevailing glucose concentration. Am J Physiol Endocrinol Metab 2015; 309:E632-9. [PMID: 26264555 DOI: 10.1152/ajpendo.00154.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 08/10/2015] [Indexed: 11/22/2022]
Abstract
In rat pancreatic islets, β-cell gene expression, survival, and subsequent acute glucose stimulation of insulin secretion (GSIS) are optimally preserved by prolonged culture at 10 mM glucose (G10) and markedly altered by culture at G5 or G30. Here, we tested whether pharmacological glucokinase (GK) activation prevents these alterations during culture or improves GSIS after culture. Rat pancreatic islets were cultured 1-7 days at G5, G10, or G30 with or without 3 μM of the GK activator Ro 28-0450 (Ro). After culture, β-cell apoptosis and islet gene mRNA levels were measured, and the acute glucose-induced increase in NAD(P)H autofluorescence, intracellular calcium concentration, and insulin secretion were tested in the absence or presence of Ro. Prolonged culture of rat islets at G5 or G30 instead of G10 triggered β-cell apoptosis and reduced their glucose responsiveness. Addition of Ro during culture differently affected β-cell survival and glucose responsiveness depending on the glucose concentration during culture: it was beneficial to β-cell survival and function at G5, detrimental at G10, and ineffective at G30. In contrast, acute GK activation with Ro increased the glucose sensitivity of islets cultured at G10 but failed at restoring β-cell glucose responsiveness after culture at G5 or G30. We conclude that pharmacological GK activation prevents the alteration of β-cell survival and function by long-term culture at G5 but mimics glucotoxicity when added to G10. The complex effects of glucose on the β-cell phenotype result from changes in glucose metabolism and not from an effect of glucose per se.
Collapse
Affiliation(s)
- Leticia P Roma
- Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Brussels, Belgium; and
| | - Jessica Duprez
- Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Brussels, Belgium; and
| | - Jean-Christophe Jonas
- Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Brussels, Belgium; and Fonds de la recherche scientifique-FNRS, Brussels, Belgium
| |
Collapse
|
43
|
You L, Wang N, Yin D, Wang L, Jin F, Zhu Y, Yuan Q, De W. Downregulation of Long Noncoding RNA Meg3 Affects Insulin Synthesis and Secretion in Mouse Pancreatic Beta Cells. J Cell Physiol 2015; 231:852-62. [PMID: 26313443 DOI: 10.1002/jcp.25175] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 08/25/2015] [Indexed: 12/15/2022]
Affiliation(s)
- LiangHui You
- Department of Biochemistry and Molecular Biology; Nanjing Medical University; Nanjing China
- Nanjing Maternity and Child Health Care Institute; Nanjing Maternity and Child Health Care Hospital Affiliated with Nanjing Medical University; Nanjing China
| | - Ning Wang
- Department of Biochemistry and Molecular Biology; Nanjing Medical University; Nanjing China
| | - DanDan Yin
- Department of Central Laboratory; The Second Affiliated Hospital of Southeast University; Nanjing China
| | - LinTao Wang
- Department of Biochemistry and Molecular Biology; Nanjing Medical University; Nanjing China
| | - FeiYan Jin
- Department of Biochemistry and Molecular Biology; Nanjing Medical University; Nanjing China
| | - YaNan Zhu
- Department of Biochemistry and Molecular Biology; Nanjing Medical University; Nanjing China
| | - QingXin Yuan
- Department of Endocrinology; First Affiliated Hospital of Nanjing Medical University; Nanjing China
| | - Wei De
- Department of Biochemistry and Molecular Biology; Nanjing Medical University; Nanjing China
| |
Collapse
|
44
|
Kong X, Yan D, Wu X, Guan Y, Ma X. Glucotoxicity inhibits cAMP-protein kinase A-potentiated glucose-stimulated insulin secretion in pancreatic β-cells. J Diabetes 2015; 7:378-85. [PMID: 24981285 DOI: 10.1111/1753-0407.12185] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 05/16/2014] [Accepted: 06/09/2014] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND The effect of incretin is markedly blunted in patients with type 2 diabetes (T2D), and this reduced effect of incretin is correlated with a diminished insulintropic potency of glucagon-like peptide-1 (GLP-1). We reported recently that GLP-1 potentiates glucose-stimulated insulin secretion (GSIS) mainly via activation of the cAMP-protein kinase A (PKA) signaling pathway in INS-1E cells under hyperglycemic conditions. In the present study, we further explored whether glucotoxicity impairs cAMP-PKA-mediated effects and its relevance to the reduced insulinotropic action of GLP-1 in hyperglycemia. METHODS Mouse islets and INS-1E cells were cultured in 30 mmol/L glucose for 72 h. The effects of glucotoxicity on cAMP-PKA-linked pathways and its insulinotropic action were then evaluated. RESULTS Chronic exposure of INS-1E cells and primary mouse islets to 30 mmol/L glucose almost abolished GSIS. The cAMP-elevating agent forskolin produced an approximate 1.9-fold increase in GSIS, significantly lower than that observed with 5.5 mmol/L glucose (~3.3-fold). Moreover, 72 h culture in the presence of 30 mmol/L glucose reduced forskolin-stimulated cAMP accumulation in β-cells. Notably, glucotoxicity reduced the expression and activity of PKA, as well as PKA-mediated effects. In contrast, glucotoxicity had no effect on the expression of Epac2, another cAMP effector. CONCLUSIONS Glucotoxicity-induced reductions in PKA and its signaling account, at least in part, for the decreased incretin effect under conditions of glucotoxicity.
Collapse
Affiliation(s)
- Xiangchen Kong
- Diabetes Center of Shenzhen University and School of Medicine, Shenzhen University, Shenzhen, China
| | | | | | | | | |
Collapse
|
45
|
Bensellam M, Montgomery MK, Luzuriaga J, Chan JY, Laybutt DR. Inhibitor of differentiation proteins protect against oxidative stress by regulating the antioxidant-mitochondrial response in mouse beta cells. Diabetologia 2015; 58:758-70. [PMID: 25636209 DOI: 10.1007/s00125-015-3503-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 12/23/2014] [Indexed: 12/21/2022]
Abstract
AIMS/HYPOTHESIS Oxidative stress is implicated in beta cell glucotoxicity in type 2 diabetes. Inhibitor of differentiation (ID) proteins are transcriptional regulators induced by hyperglycaemia in islets, but the mechanisms involved and their role in beta cells are not clear. Here we investigated whether or not oxidative stress regulates ID levels in beta cells and the role of ID proteins in beta cells during oxidative stress. METHODS MIN6 cells were cultured in H2O2 or ribose to induce oxidative stress. ID1, ID3 and small MAF proteins (MAFF, MAFG and MAFK) were inhibited using small interfering RNA. Isolated islets from Id1(-/-), Id3(-/-) and diabetic db/db mice were used. RESULTS ID1-4 expression was upregulated in vivo in the islets of diabetic db/db mice and stimulated in vitro by ribose and H2O2. Id1/3 inhibition reduced the expression of multiple antioxidant genes and potentiated oxidative stress-induced apoptosis. This finding was associated with increased levels of intracellular reactive oxygen species, altered mitochondrial morphology and reduced expression of Tfam, which encodes a mitochondrial transcription factor, and respiratory chain components. Id1/3 inhibition also reduced the expression of small MAF transcription factors (MafF, MafG and MafK), interacting partners of nuclear factor, erythroid 2-like 2 (NFE2L2), master regulator of the antioxidant response. Inhibition of small MAFs reduced the expression of antioxidant genes and potentiated oxidative stress-induced apoptosis, thus recapitulating the effects of Id1/3 inhibition. CONCLUSIONS/INTERPRETATION Our study identifies IDs as a novel family of oxidative stress-responsive proteins in beta cells. IDs are crucial regulators of the adaptive antioxidant-mitochondrial response that promotes beta cell survival during oxidative stress through a novel link to the NFE2L2-small MAF pathway.
Collapse
Affiliation(s)
- Mohammed Bensellam
- Garvan Institute of Medical Research, St Vincent's Hospital, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia
| | | | | | | | | |
Collapse
|
46
|
Goyvaerts L, Lemaire K, Arijs I, Auffret J, Granvik M, Van Lommel L, Binart N, in’t Veld P, Schuit F, Schraenen A. Prolactin receptors and placental lactogen drive male mouse pancreatic islets to pregnancy-related mRNA changes. PLoS One 2015; 10:e0121868. [PMID: 25816302 PMCID: PMC4376745 DOI: 10.1371/journal.pone.0121868] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 02/19/2015] [Indexed: 12/03/2022] Open
Abstract
Pregnancy requires a higher functional beta cell mass and this is associated with profound changes in the gene expression profile of pancreatic islets. Taking Tph1 as a sensitive marker for pregnancy-related islet mRNA expression in female mice, we previously identified prolactin receptors and placental lactogen as key signalling molecules. Since beta cells from male mice also express prolactin receptors, the question arose whether male and female islets have the same phenotypic resilience at the mRNA level during pregnancy. We addressed this question in vitro, by stimulating cultured islets with placental lactogen and in vivo, by transplanting male or female islets into female acceptor mice. Additionally, the islet mRNA expression pattern of pregnant prolactin receptor deficient mice was compared with that of their pregnant wild-type littermates. When cultured with placental lactogen, or when transplanted in female recipients that became pregnant (day 12.5), male islets induced the 'islet pregnancy gene signature', which we defined as the 12 highest induced genes in non-transplanted female islets at day 12.5 of pregnancy. In addition, serotonin immunoreactivity and beta cell proliferation was also induced in these male transplanted islets at day 12.5 of pregnancy. In order to further investigate the importance of prolactin receptors in these mRNA changes we used a prolactin receptor deficient mouse model. For the 12 genes of the signature, which are highly induced in control pregnant mice, no significant induction of mRNA transcripts was found at day 9.5 of pregnancy. Together, our results support the key role of placental lactogen as a circulating factor that can trigger the pregnancy mRNA profile in both male and female beta cells.
Collapse
Affiliation(s)
- Lotte Goyvaerts
- Gene Expression Unit, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Katleen Lemaire
- Gene Expression Unit, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Ingrid Arijs
- Gene Expression Unit, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
- Department of Clinical and Experimental Medicine, Translational Research Center for Gastrointestinal Disorders (TARGID), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium
| | - Julien Auffret
- Inserm U693, Faculté de Médecine Paris-Sud, Université Paris-Sud, Le Kremlin-Bicêtre, France
| | - Mikaela Granvik
- Gene Expression Unit, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Leentje Van Lommel
- Gene Expression Unit, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Nadine Binart
- Inserm U693, Faculté de Médecine Paris-Sud, Université Paris-Sud, Le Kremlin-Bicêtre, France
| | - Peter in’t Veld
- Department of Pathology, Vrije Universiteit Brussel, Jette, Belgium
| | - Frans Schuit
- Gene Expression Unit, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Anica Schraenen
- Gene Expression Unit, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| |
Collapse
|
47
|
Broniowska KA, Oleson BJ, McGraw J, Naatz A, Mathews CE, Corbett JA. How the location of superoxide generation influences the β-cell response to nitric oxide. J Biol Chem 2015; 290:7952-60. [PMID: 25648890 DOI: 10.1074/jbc.m114.627869] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cytokines impair the function and decrease the viability of insulin-producing β-cells by a pathway that requires the expression of inducible nitric oxide synthase (iNOS) and generation of high levels of nitric oxide. In addition to nitric oxide, excessive formation of reactive oxygen species, such as superoxide and hydrogen peroxide, has been shown to cause β-cell damage. Although the reaction of nitric oxide with superoxide results in the formation of peroxynitrite, we have shown that β-cells do not have the capacity to produce this powerful oxidant in response to cytokines. When β-cells are forced to generate peroxynitrite using nitric oxide donors and superoxide-generating redox cycling agents, superoxide scavenges nitric oxide and prevents the inhibitory and destructive actions of nitric oxide on mitochondrial oxidative metabolism and β-cell viability. In this study, we show that the β-cell response to nitric oxide is regulated by the location of superoxide generation. Nitric oxide freely diffuses through cell membranes, and it reacts with superoxide produced within cells and in the extracellular space, generating peroxynitrite. However, only when it is produced within cells does superoxide attenuate nitric oxide-induced mitochondrial dysfunction, gene expression, and toxicity. These findings suggest that the location of radical generation and the site of radical reactions are key determinants in the functional response of β-cells to reactive oxygen species and reactive nitrogen species. Although nitric oxide is freely diffusible, its biological function can be controlled by the local generation of superoxide, such that when this reaction occurs within β-cells, superoxide protects β-cells by scavenging nitric oxide.
Collapse
Affiliation(s)
- Katarzyna A Broniowska
- From the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 and
| | - Bryndon J Oleson
- From the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 and
| | - Jennifer McGraw
- From the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 and
| | - Aaron Naatz
- From the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 and
| | - Clayton E Mathews
- the Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida 32610
| | - John A Corbett
- From the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 and
| |
Collapse
|
48
|
Ma L, Fu Y, Yu L, Li X, Zheng W, Chen T. Ruthenium complexes as inhibitors of human islet amyloid polypeptide aggregation, an effect that prevents beta cell apoptosis. RSC Adv 2015. [DOI: 10.1039/c4ra15152f] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Herein we show that ruthenium complexes could inhibit fibrosis of hIAPP and protect the hIAPP-induced cell damage by suppressing ROS generation, indicating the application potential of the complexes in treatment of T2DM by targeting hIAPP.
Collapse
Affiliation(s)
- Lijuan Ma
- Department of Chemistry
- Jinan University
- Guangzhou 510632
- China
| | - Yuanting Fu
- Department of Chemistry
- Jinan University
- Guangzhou 510632
- China
| | - Lianling Yu
- Department of Chemistry
- Jinan University
- Guangzhou 510632
- China
| | - Xiaoling Li
- Department of Chemistry
- Jinan University
- Guangzhou 510632
- China
| | - Wenjie Zheng
- Department of Chemistry
- Jinan University
- Guangzhou 510632
- China
| | - Tianfeng Chen
- Department of Chemistry
- Jinan University
- Guangzhou 510632
- China
| |
Collapse
|
49
|
Ma X, Guan Y, Hua X. Glucagon-like peptide 1-potentiated insulin secretion and proliferation of pancreatic β-cells. J Diabetes 2014; 6:394-402. [PMID: 24725840 DOI: 10.1111/1753-0407.12161] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 03/28/2014] [Accepted: 04/07/2014] [Indexed: 02/06/2023] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is the primary incretin hormone secreted from the intestine upon uptake of food to stimulate insulin secretion from pancreatic β-cells. GLP-1 exerts its effects by binding to its G-protein coupled receptors and subsequently activating adenylate cyclase, leading to generation of cyclic adenosine monophosphate (cAMP). cAMP stimulates insulin secretion via activation of its effectors PKA and Epac2 in pancreatic β-cells. In addition to its insulinotropic effects, GLP-1 also preserves pancreatic β-cell mass by stimulating β-cell proliferation. Unlike the action of sulphonylureas in lowering blood glucose levels, action of GLP-1 is affected by and interplays with glucose levels. Due to such advantages, GLP-1-based therapeutics have been rapidly developed and used clinically for treatment of type 2 diabetes. However, molecular mechanisms underlying how GLP-1 potentiates diminished glucose-stimulated insulin secretion and β-cell proliferation under diabetic conditions are not well understood. Here, we review the actions of GLP-1 in regulation of insulin secretion and pancreatic β-cell proliferation.
Collapse
Affiliation(s)
- Xiaosong Ma
- Shenzhen University Diabetes Center, Shenzhen, China
| | | | | |
Collapse
|
50
|
Acute nutrient regulation of the mitochondrial glutathione redox state in pancreatic β-cells. Biochem J 2014; 460:411-23. [PMID: 24678915 DOI: 10.1042/bj20131361] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The glucose stimulation of insulin secretion by pancreatic β-cells depends on increased production of metabolic coupling factors, among which changes in NADPH and ROS (reactive oxygen species) may alter the glutathione redox state (EGSH) and signal through changes in thiol oxidation. However, whether nutrients affect EGSH in β-cell subcellular compartments is unknown. Using redox-sensitive GFP2 fused to glutaredoxin 1 and its mitochondria-targeted form, we studied the acute nutrient regulation of EGSH in the cytosol/nucleus or the mitochondrial matrix of rat islet cells. These probes were mainly expressed in β-cells and reacted to low concentrations of exogenous H2O2 and menadione. Under control conditions, cytosolic/nuclear EGSH was close to -300 mV and unaffected by glucose (from 0 to 30 mM). In comparison, mitochondrial EGSH was less negative and rapidly regulated by glucose and other nutrients, ranging from -280 mV in the absence of glucose to -299 mV in 30 mM glucose. These changes were largely independent from changes in intracellular Ca(2+) concentration and in mitochondrial pH. They were unaffected by overexpression of SOD2 (superoxide dismutase 2) and mitochondria-targeted catalase, but were inversely correlated with changes in NAD(P)H autofluorescence, suggesting that they indirectly resulted from increased NADPH availability rather than from changes in ROS concentration. Interestingly, the opposite regulation of mitochondrial EGSH and NAD(P)H autofluorescence by glucose was also observed in human islets isolated from two donors. In conclusion, the present study demonstrates that glucose and other nutrients acutely reduce mitochondrial, but not cytosolic/nuclear, EGSH in pancreatic β-cells under control conditions.
Collapse
|